Arlington Snap2IT® Cable Connector, Duplex Straight, 3/8 in Trade, 3/8 in Knockout, Cable Openings: 0.405 to 0.612 in, 2 Conductors, Aluminum/Steel/Flex/AC/AC90/HCF/MC/MCI-A Cable, Snap-In Connection, Die Cast Zinc, Silver, 2.154 in H x 1.738 in W Dimensions. Arlington Snap2IT® connectors are designed for safe and fast installations of flex, MC, AC and HCF cable and cover the widest cable ranges in the industry. They save time too-about 17 s per fitting. Just snap the fitting onto the cable, then into the electrical box. No tools are required for the installation.