FastenMaster FMHLGM412-50 HeadLOK Heavy-Duty Flathead Fastener, 4-1/2 Inches, 50-Count

Screws do what screws are supposed to do. Hold wood together fine. Really big heads, but not flat underneath so predrilling thin veneer materials is a must. Cons: Did not come with driver bit in either box I bought. No response for over 3 weeks from seller on making that right or not. Now it is past return or claim cutoff. False advertising to say driver included then not provide. ONE star due to the above.

We no longer use lag screws for any application, these and the other structural fasteners by FastenMaster and others have made lag screws obsolete. No need to pre-drill in most applications and I have yet to break one or strip out a head. They are also stronger then lag screws that are 50% larger in diameter. I.E. A 1/4 Headlok is stronger then a 3/8 standard lag screw. Forget about these pulling out either, you will have to destroy the wood beam/header/joist before these will pull out.

great screws. I used these to secure pieces of 2x4s when building shelves. I did have to drill pilot holes when screwing near ends of the lumber as the screws split the wood when I didnt drill pilot holes

Use these screws extensively on a deck. Biggest plus is the flat head.

robust, easy to fasten, should hold securely for a long time!

Totally happy with these. Pros: the included spider bit works great driving these fasteners into redwood, pine and cedar. No experience with hardwoods. Depending on the wood itself (adjacent knots, etc), these will counter-sink themselves without stripping, leaving a flush finish. Much nice than the traditional hex-head timber lox. These have a wider diameter head, so they hold very well. Cons: none. Application -- building a pergola from recycled redwood planks.

Drives like a champ. Way easier and faster than the 3/8 bolt it replaces. Hoping the engineers did their homework because these fasteners are too good to believe.

These are great lags/screws. I bought another box after using this whole box. They do not strip and hold up very heavy items in my home gym and garage. I definitely recommend these.

...and a retaining wall of pressure treated 6x6 lumber. The result is so solid I know I wont need to redo it in the future.

Weve used a lot of different fasteners to hold deck framing together, and these are hands down the best so far. We drill a pilot slightly smaller and the same depth as the the smooth shank, then drive them with a cordless impact gun until they are flush. They are great a pulling and holding slightly warped framing lumber into line.