Bostitch sb hc50fn concrete block nailer 20 50mm nails bostitch sb hc50fn p this concrete block nailer 20 50mm from bostitch is a powerful heavy duty nail tool which has been manufactured to a high standard and is ideal for driving high carbon zinc dichromate hardened nails into concrete blocks to 7 newtons p p equipped with sturdy aluminium housing plus numerous great features including a no mar tip dial a depth adjustable exhaust sequential trip and bottom loading all of which mak