Model # FMHLGM412-12

Internet # 202268269

Store SKU # 517046

HeadLok 4-1/2 in. Heavy Duty Flathead Fastener - (12-Pack)



Model # FMHLGM412-12

Internet # 202268269

Store SKU # 517046

Store SO SKU # 336802

Save time, money and labor costs! HeadLok eliminates the need to predrill and hand-ratchet in 3/8 in. galvanized lag screws in wood-to-wood projects. HeadLoks aggressive threading and sharp gimlet point allows it to zip right into wood or OSB without pre-drilling. Plus, the wafer head eliminates the need for washers and offers increased pull through strength. Perfect for deck framing, stair stringers, fencing, cabinets, and more! Sizes are perfect for virtually any dimensional wood-to-wood project.

  • Nationally code compliant. Stronger design shear values than 3/8 in. lag screws
  • No pre-drilling. Zip right in
  • Patented spider drive virtually eliminates cam-out
  • Guaranteed corrosion resistance for the life of the project. ACQ approved
  • Free spider driver bit in every package
  • American made

Info & Guides

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Assembled Depth (in.) 
.189 in 
Assembled Height (in.) 
4.5 in 
Assembled Width (in.) 
.189 in 
Screw Length 
4-1/2 in 
Drive Style 
Driver bit included 
Fastener Callout Size 
4 1/2" 
Fastener Plating 
Fastener Thread Type 
Fastener Type 
Specialty Fastener 
Fastener/Connector Material 
Finish Family 
Head Style 
Measurement Standard 
Package Quantity 
Primary Use 
Wood-to-wood construction i.e. decking, cabinets, stair stringers, SIP pannels, and more! 
Product Weight (lb.) 
0.6 lb 
Self drilling 
Self tapping 
Tamper Resistant 
Warranty / Certifications
Manufacturer Warranty 
FastenMaster fully guarantees HeadLok against rusting or streaking for the lifetime of the project. Please see the following link for further details at: http://www.fastenmaster.com/Files/TechnicalCodeFiles/20/DocumentFile/FMGYHLGM20090901.pdf 


Size: #0
Screw Length: 4-1/2 in
Fastener Thread Type: Coarse
Drive Style: Star
Head Style: Flat
Fastener/Connector Material: Steel
Measurement Standard: SAE
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HeadLok 4-1/2 in. Heavy Duty Flathead Fastener - (12-Pack)
HeadLok 4-1/2 in. Heavy Duty Flathead Fastener - (12-Pack)

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What is shear strength

This question is from HeadLok 4-1/2 in. Heavy Duty Flathead Fastener (50-Box)
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December 17, 2015
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Rated 4.6 out of 5 by 5 reviewers.
Rated 5.0 out of 5.0 by Homemade Camper Project These screws are advertised as being stronger than regular lag bolts. I purchased these in two different lengths for use in my project. I already had a partial box of these in 6" length from a previous project. I find that pre drilling a pilot hole before installing is the best way to go in the Douglas Fir I am using. I especially like the fact that an installation tool is provided with each box of screws. The screws have an aggressive thread which provides a great grip into lumber. Holding power is what I wanted and I believe these screws provide just that. February 23, 2016
Rated 5.0 out of 5.0 by This product is versatile, strong and virtually invisible The HeadLok line of fasteners from Fastenmaster provides utility and ease of use. We use them all over for decks, railings and shade structures. August 21, 2013
Rated 5.0 out of 5.0 by Great product. Warrantied for life of project. I will periodically inspect corrosion protection. Saves time. Saves money in bulk. No need for rafter hangers. Corrosion resistant for life. Great product. August 25, 2015
Rated 3.0 out of 5.0 by great screw, lousy bits I love the screws. They drive easily into PT timbers with impact drivers. The bits however are way too soft and self-destruct very easily. I went through 13 spider bits for only 150 screws. So if you buy a bucket load of screws, be prepared to buy all of the spider bits available in the store. I used two impact drivers for this particular job. The first was a Milwaukee 2563 cordless impact driver with 3 torque setting options. To drive the 4.5 inch screw, the most powerful setting was needed. It would come close to flush driving the screws in PT timbers and boards. The only problem was the battery would die after only a dozen screws. So I don't recommend using that tool with this size screw. The second impact driver was a Porter Cable 120v driver. It had no problem power wise and would easily drive the screws. The only concern is it does not have any torque setting options. So you have to be careful when driving to stop before the head gets close to being set how you like or need it to be. I'm looking for a 120v impact driver with torque settings. That or another cordless impact driver with torque settings and more power or larger battery capacity. Again, love the screws, hate the spider bits. June 22, 2013
Rated 5.0 out of 5.0 by Super screws home depot had these screws cheaper than anyone else online. these scews are excellent for all application that supper hold is needed and isnt seen or cosmetic isnt a issue they have large heads they are stronger than most lag bolts easily installed with my 14v cordless May 2, 2011
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