Quality back plates for rotary tables to mount chucks on them Made of tool steel. Precisely machined. Countered bored so that t nuts sits inside them perfectly. Supplied with 3 x t nuts + bolts as per back plate 's size. Recess 95 mm. 3 x 8 mm thread drills to mount a 3 jaw chuck & m8 counter bored to attached the back plate with the rotary table's t slot.