4 pack of 1 1/4 IN alloy screws used to install your shelf and racks into studs or hollow dry wall. When installed into wood they can old over 100+ per flange. 3/8th inch countersunk heads. (#7 screws)all of our flanges use 1/4th inch mounting holes. Installed into drywall with anchors we dont recommend more than 50lbs per set of brackets.