Free Shipping

on orders over $99

Worry-free Returns

365 day return policy


The ideal fastener for wood-to-wood applications, the HeadLOK Heavy Duty Flathead Fastener by FastenMaster. The unique design gives the HeadLOK screws a higher shear strength than regular 3/8 inch lag screws, eliminating the need to pre-drill, and featuring a non-countersinking head. Crafted from 1022 Carbon Steel Grade with a corrosion resistant coating, HeadLOK screws will help you save time and money on projects such as deck frames, cabinetry, fences, and more. ACQ-rated for use with pressure treated lumber, the HeadLOK screws are not designed to be used within 1000 feet of salt water.

HeadLOK Screws by FastenMaster feature a wafer-style head with a bit engaging Spider drive.

They are available in the lengths of 2-7/8 inches, 4-1/2 inches, and 6 inches; and in packs of 12, 50, 250, and 500 screws to accommodate the project you need.

Note: Not all lengths are available in all pack quantities.


DecksDirect # 5535

Installation Instructions (450 KB) 

ICC-ES Evaluation Report (281 KB) 

Technical Evaluation Report (487 KB) 

Drive TypeSpider drive
Head TypeWafer head
Screw Length2-7/8 in, 4-1/2 in, and 6 in
Screw Size5/16 in


Material Type1022 Carbon Steel Grade with a proprietary corrosion resistant coating
Pack Size

12 pack, 50 pack, 250 pack, and 500 pack
Note: Not all lengths are available in all pack quantities.

Coverage Estimaten/a
Included Accessories2 in spider drive bit
WarrantyHeadLOK Guarantee of Performance
OtherACQ approved
Not designed for use within 1000 ft of salt water
Made in the U.S.A.
ThruLOK Screw Bolts By FastenMaster - 6-1/4 in - 24 pack - Packaging
Starting at: $34.99
RSS Rugged Structural Screws By GRK Fasteners - 3/8 in x 6 in - 50 Pro Pack
Starting at: $21.99
Grace Vycor Plus Self-Adhering Flashing Tape
Starting at: $29.99
The Collated Cortex Hidden Fastening System for AZEK Trim by FastenMaster includes the Cortex plugs, installation screws, and Cortex setting tools.
Starting at: $182.99

Reviews & Questions