about us

Zoro has a simple mission—
We help small business stay competitive!

We do this by offering more than 750,000 great products at super low prices. Small businesses have historically been at a disadvantage to larger companies who can buy stuff at lower prices because of their size. We want to change that!

Zoro has most of the products that the “big guys” have and we offer every single one of them at an everyday low price. There are no complex discount structures to understand. Every customer pays the same low price for an item—whether you want to buy one or one thousand!

We have our headquarters in Buffalo Grove, IL—though we are petitioning the town to rename itself Fox Grove. (We’re coming for you, Buffaloes.) And we ship orders out of six warehouses strategically located across the country. More specifically, they are in California (one in sunny SoCal and one in breezy NorCal), Illinois (the Land of Lincoln), South Carolina (the Land of Mustard BBQ sauce), Texas (the warehouse there is bigger), and Wisconsin (the Land of the Fonzie Statue).

Like you, we believe that the key to success is to always put our customers first.

contact us

We live for the moments that we can make you happy—that’s the truth!

Most of our business occurs through the internet. However, we know that there are times when you need to communicate with a person. Our customer service staff is here to help you. You can contact us in the way that works best for you.

Our customer service hours are Monday thru Friday from 7am to 7pm (CT) and Saturdays from 9am to 2pm (CT).

Si necesita ayuda en español, por favor, comuníquese con nosotros por teléfono. Gracias.

855.BUY.ZORO (855.289.9676)

855.FAX.ZORO (855.329.9676)

Contact Customer Service

using our site

Zoro has designed a unique and intuitive product search feature.

All you need to do is select the product attribute values you are looking for within your search results (size, color, material, etc.) by clicking on the value you want, and the products that meet the criteria you have chosen are immediately shown in a table right below where you made your selections.

The more specific you are in your attribute selections—the narrower the search results will become in your very own “custom made” product table!

If you prefer to search using manufacturer model #, a competitor's part number or a Zoro part number, just enter that number into the “search bar” at the top of the page, you will immediately be taken to a page that contains the item.

catalog request

Top Products Guide

Right now, Zoro’s FULL CATALOG is our website. So, you have full access to it all the time.

To request our Top Products Guide, please click below and fill out the form. Catalog requests may take up to 3 weeks to fulfill so we have also included a pdf version of the catalog to download.

In addition, you will automatically be placed on the mailing list once you buy from Zoro.

resource den

Resource Den

Need some help? We are here for you! We have awesome supplemental resources to help you be prepared, find the right items, and get the job done.

UNC BO Partial Thread Std. Head Cap Screw

Socket Head Cap Screws
Description: Item: Socket Head Cap Screw; Thread Style: Partially Threaded; Finish: Black Oxide; Head Style: Standard; Drive Type: Hex Socket; Class: 3A; Material: Alloy Steel; Thread Type: UNC
Product Options
ImageRockwell HardnessMeets/ExceedsMeetsThread LengthSelf-Locking ElementDrive SizeTemp. Range (F)Thread SizeHead HeightDecimal EquivalentHead Dia.Length under HeadThread DirectionMin. Tensile Strength (PSI)RestrictionPackage
Mfr.#ZoroItem#Ships fromPriceQty.
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.31-1/2"-3/8"-1/2-130.500"0.375"0.750"5-1/2"Right Handed180,000 254XE93G2551717
C39 to C44ASTM A574, ANSI B18.3ASTM A574, ANSI B18.37/8"-5/32"-10-240.190"0.190"0.312"2-1/2"Right Hand180,000 256ZE31G0331326
C39 to C44ASTM A574, ANSI B18.3ASTM A574, ANSI B18.33/4"-3/32"-4-400.112"0.112"0.183"1-1/4"Right Hand180,000 100U07000.011.0125G2029343
C39 to C44ASTM A574, ANSI B18.3ASTM A574, ANSI B18.31-3/8"-5/16"-7/16-140.437"0.437"0.656"2-1/2"Right Hand180,000 10U07000.043.0250G0608973
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.31-1/8"-1/4"-5/16-180.312"0.250"0.469"1-3/4"Right Handed180,000 1004XE51G3473181
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.31-1/4"-5/16"-3/8-160.375"0.312"0.561"2-1/4"Right Handed180,000 504XE67G1679745
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.31-1/4"-5/16"-3/8-160.375"0.312"0.561"3-1/4"Right Handed180,000 504XE71G3093781
C39 to C44ASTM A574, ANSI B18.3ASTM A574, ANSI B18.31"-3/16"-1/4-200.250"0.250"0.375"3-1/2"Right Hand180,000 25U07000.025.0350G1694201
C39 to C44ASTM A574, ANSI B18.3ASTM A574, ANSI B18.31-3/8"-5/16"-7/16-140.437"0.437"0.656"3-1/2"Right Handed180,000 103MB74G0246251
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.31-3/4"-1/2"-5/8-110.625"0.500"0.938"4-1/2"Right Handed170,000 204XU17G3389312
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.31-1/2"-3/8"-1/2-130.500"0.375"0.750"2-1/4"Right Handed180,000 254XE84G1950523
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.31"-3/16"-1/4-200.250"0.188"0.375"1-1/2"Right Handed180,000 100U07000.025.0150G0254152
C39 to C45ASME B18.3 2002ASME B18.3 20021-1/4"Nylon Patch5/16"2503/8-160.375"0.313"0.562"2-1/2"Right Handed180,000 101GA66G0966314
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.31"-3/16"-1/4-200.250"0.188"0.375"2-3/4"Right Handed180,000 1004XE42G1913195
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.31-1/8"-1/4"-5/16-180.312"0.250"0.469"2-1/4"Right Handed180,000 1004XE53G3279306
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.31"-3/16"-1/4-200.250"0.188"0.375"2-1/2"Right Handed180,000 1004XE41G2629566
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.37/8"-9/64"-8-320.164"0.141"0.270"2-1/2"Right Handed180,000 100U07000.016.0250G3398674
C39 to C45ASME B18.3 2002ASME B18.3 20021-1/8"Nylon Patch1/4"2505/16-180.313"0.250"0.469"1-3/4"Right Handed180,000 101GA50G3401544
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.31-1/4"-5/16"-3/8-160.375"0.312"0.561"1-3/4"Right Handed180,000 504XE65G1057892
C39 to C44ASTM A574, ANSI B18.3ASTM A574, ANSI B18.31-3/8"-5/16"-7/16-140.437"0.437"0.656"2-3/4"Right Hand180,000 10U07000.043.0275G3118202
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.37/8"-9/64"-8-320.164"0.141"0.270"1-3/4"Right Handed180,000 100U07000.016.0175G0445925
C39 to C44ASTM A574, ANSI B18.3ASTM A574, ANSI B18.31-3/8"-5/16"-7/16-140.437"0.437"0.656"4-1/2"Right Handed180,000 103MB82G2141465
C39 to C44ASTM A574, ANSI B18.3ASTM A574, ANSI B18.31-3/8"-5/16"-7/16-140.437"0.437"0.656"2-1/4"Right Hand180,000 10U07000.043.0225G1396087
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.31-1/8"-1/4"-5/16-180.312"0.250"0.469"2-1/2"Right Handed180,000 1004XE54G1019505
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.31-1/2"-3/8"-1/2-130.500"0.375"0.750"2-3/4"Right Handed180,000 254XE86G3385137
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.33/4"-7/64"-6-320.138"0.109"0.226"1-1/2"Right Handed180,000
C39 to C44ASTM A574, ANSI B18.3ASTM A574, ANSI B18.31-1/8"-1/4"-5/16-180.312"0.312"0.469"7-1/2"Right Hand180,000 56ZU55G0531517
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.31-1/2"-3/8"-1/2-130.500"0.375"0.750"3-1/2"Right Handed180,000 254XE89G2772987
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.31-1/4"-5/16"-3/8-160.375"0.312"0.561"2-3/4"Right Handed180,000 504XE69G2775166
C39 to C45ASME B18.3 2002ASME B18.3 20021-1/4"Nylon Patch5/16"2503/8-160.375"0.313"0.562"2-1/4"Right Handed180,000 101GA65G2905691
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.37/8"-5/32"-10-240.190"0.156"0.312"1-1/2"Right Handed180,000 100U07000.019.0150G3361522
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.31-3/4"-1/2"-5/8-110.625"0.500"0.938"2-1/2"Right Handed170,000 254XU12G0974967
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.37/8"-5/32"-10-240.190"0.156"0.312"1-1/4"Right Handed180,000 100U07000.019.0125G1654021
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.31-1/2"-3/8"-1/2-130.500"0.375"0.750"3-1/4"Right Handed180,000 254XE88G2407431
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.31-1/8"-1/4"-5/16-180.312"0.250"0.469"2-3/4"Right Handed180,000 1004XE55G1282111
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.37/8"-9/64"-8-320.164"0.141"0.270"1-1/2"Right Handed180,000 100U07000.016.0150G1007894
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.37/8"-5/32"-10-240.190"0.156"0.312"1-3/4"Right Handed180,000 100U07000.019.0175G1896517
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.37/8"-9/64"-8-320.164"0.141"0.270"1-1/4"Right Handed180,000 100U07000.016.0125G1899527
C38 to C43ASME/ANSI B18.3ASME/ANSI B18.31-1/2"-3/8"-1/2-130.500"0.375"0.750"4-1/2"Right Handed180,000 254XE91G3168356
C39 to C45ASME B18.3 2002ASME B18.3 20021"Nylon Patch3/16"2501/4-200.250"0.188"0.375"2-1/2"Right Handed180,000 101GA36G3177702

1: California Proposition 65 This product contains a chemical known to the State of California to cause birth defects or other reproductive harm.

2: California Proposition 65 This product contains a chemical known to the State of California to cause cancer.

: Ships from Zoro.

: Ships from manufacturer.