Wrench Set Combination 12 pc N-PowerFit Drive- Increased strength and reduces rounding or fastener damage by distributing stress through a gentle arc in the bore by enlarging the contact surface. Open end has reinforced teeth to prevent cracking and breaking. Angle rise of 15 degree for box end. Compact external diameter is among smallest in the world and ideal for tight spaces. Contains NMS2-055, NMS2-07, NMS2-08, NMS2-10, NMS2-12, NMS2-13, NMS2-14, NMS2-17, NMS2-19, NMS2-21, NMS2-22, NMS2-24 NTMS212