The 750 series right angle block feature two 3/4 inch holes at 90 degrees to each other. This block is the workhorse of the Berkey System. These blocks are available in both a left and right hand version. This allows access to the fastener even if you have two blocks side by side. An equal number of each is recommended. You can never have too many of these. All 750 series components are compatible with any 19 mm camera gear.