This flanged button head socket cap screw is made out of steel with a black zinc finish. The low domed head with a wider bearing surface offer a finished appearance, making them an ideal choice when a neat appearance is desired. This bolt comes with a 0.56" diameter flange head and full thread length of 0.75" with a 5/32 allen hex drive. Thread size is 1/4-20. Used with t-nuts to mount brackets and plates to aluminum extrusions. Quick installation and can be re-purposed over and over. Perfect for your extruded rail projects! Button head screws have a low domed head with a wider bearing surface than standard heads, and they offer a finished appearance, making them an ideal choice when a neat appearance is desired.