A - cylinder, steel or AL, .870 o.d. dia x 3/4" long with 1/8" center hole drilled thru.
B - cylinder, steel or AL, 1" o.d. x 3/4" long with 1/8" center hole drilled thru.
Normal machining tolerances and finish OK. B can be from standard 1" bar stock.
Quote one each (proto for approval) and 6 & 12 each.