Push-in Wire Connector. Solid and Stranded Wires (No. 22-12 AWG). Stranded Conductors DO NOT need to be tinned. Polycarbonate Housing: Clear for easy Inspection. Inline Construction(NOT Stacked). Test Slot in front permits easy access for voltage tester. Clamp Unit: Copper, Tin Plated, Stainless Steel Spring, Steel frame Zinc Plated. Strip Length: (.43 inch) (11mm). Voltage Rating Building Wiring: 600V Max.