Spec and size: SM-25, SM-30, SM-35, SM-40, SM-51, SM- 76 can be round nut or hexagon nut. Busbar insulator:Features:1) Tensile strength: 650lbs2) Torque strength (ft lbs): 103) Voltage withstand: 12kV4) Screw: 8mm5) Weight: 86gSpec and size:SM-25, SM-30, SM-35, SM-40, SM-51, SM- 76can be round nut or hexagon nut.