The function and purpose of the square head screw determine the size of the head from the bolt. This type of screw is used to tighten the nut in addition to two sections. Square head screws ended up the field standard just before hex bolts obtained relevance. Yankee: This is https://types-of-metal-ceiling15936.activablog.com/28903372/an-unbiased-view-of-types-of-screw-heads-uk