IDEAL Can-Snap™ Non-Metallic Box Connectors

Canadian electricians are using Can-Snap to secure and protect NM cable faster and more conveniently than ever before! Can-Snap SAVES TIME - Installs faster & easier than traditional cable clamps - simply snap in; PROTECTS - Protects cable from knock-out damage and provides strain-relief; SECURES - 1/2" and 3/4" connectors secure nonmetallic cable sizes from 14/2 to 6/3.
• Quick installation - simply snap in - no tools required
• Protection from rough knock-out edges
• Secures cable and provides strain relief
• Available for 1/2” and 3/4” knockouts
• Convenient packaging
• Proudly made in Canada!

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Is it possible to snap these in around a cable that is already wired in a box? Can the Romex fit through the slit on the side and hold down the flap until it snaps in? Just trying to avoid redoing the wiring.