Metallics GDS4M 8 x 2-1/2 in. Flat Head Phillips Deck Screws - Steel Yellow Zinc - Coarse Threads - Each

The GDS4M ships as a box of 1,000, which is also the order minimum. If you need a smaller count or a different length, Metallics offers other sizes and quantities by request rather than off the shelf in this configuration.

Yes. At 2-1/2 inches the GDS4M passes through a nominal 1-1/2 inch thick 2x member and leaves roughly an inch of thread biting into the receiving piece, with nothing protruding. The coarse UNC thread is what gives the bite in softwood framing.

The GDS4M is steel with a yellow zinc dichromate finish and Metallics lists it for all-weather wood applications, so it is intended for exterior framing and decking work. Yellow zinc dichromate is a coating, not stainless, so for direct contact with ACQ-treated lumber in standing wet or coastal conditions a stainless or polymer-coated screw is the safer call.

A #2 Phillips driver. The GDS4M is a flat head screw with a Phillips drive, and the specified driver size is #2, so a standard PH2 bit in an impact driver or drill handles the whole box.

Metallics lists the GDS4M as both ARRA compliant and Buy American compliant, which is what a public-works or federally funded spec usually asks for. Country of origin is listed as multiple, so if your contract requires a single named origin on the submittal, flag it when you order.

Coarse for wood. The GDS4M uses a coarse UNC thread, which is the correct pitch for softwood and treated lumber because the deeper, wider-spaced thread grabs the fiber and resists pull-out. Fine thread is for harder material and metal substrates, where it would strip in a 2x.

Metallics catalogs the GDS series for the electrical, plumbing, heating and air conditioning trades as well as all-weather wood work. Electricians use a #8 x 2-1/2 flat head coarse-thread screw for mounting boxes, backer blocks, strut backing, and panel plywood to wood studs, which is why it sits in an electrical fastener line rather than a lumberyard line.

Flat head with a Phillips recess, so it self-countersinks flush in softwood when driven home and the coarse thread pulls it down. In hardwood, or near board ends where splitting is a risk, pre-drill and counterbore.

The box runs 10.42 lbs and measures 7.25 x 6.25 x 6 inches, so a full 1,000-count box fits easily in a gang box or on a cart without repacking.