UNC, BZP, part thread hex bolts which are also know as hexagon bolts, or hex head bolts.

UNC - BZP Grade 5 Hex Bolts - ANSI B18.2.1

UNC hex bolts in an extensive range of sizes and at competitive prices. Also known as hexagon bolts, they are manufactured from grade 5 steel with a bright zinc plating (BZP). The zinc plating provides a mid-level of corrosion resistance making them effective in both internal and external applications. With a hex head, they are versatile and widely used across many industries.