Strong 8.8 grade 6mm thread steel bolts. •Flange design with 8mm hex head. •Kit comes with a six compartment plastic case and 25 of each of the following bolts; 6×12, 6×16, 6×20, 6×25, 6×30, and 6×35 (150 bolts!) •Individual sizes can be purchased separately in bags of 25.