18-8 Stainless Steel Phillips Flat Head Machine Screw Kit - 512pcs - Assorted stainless steel Phillips Flat Head Machine Screws in inch sizes #4-40 through 1/4"-20 in a durable heavy plastic box. Lengths up to 1-1/2". This fastener kit includes matching stainless steel hex nuts for the machine screws. All fasteners in this kit are 18-8 stainless steel. See table below for more specifications.