3/4" ALUMINUM Domed Knurled Knob, 1/4-20 Blind TAPPED Hole.  Minimum depth 5/64".

Available direct from the manufacturer.

Shipping discount applied when multiple items are purchased.

Hole diameter 1/4

A   3/4

B   5/8

C   1/2

D   1/4

E   3/8

R   5/64