Spring closures are versatile; they're great for most corded jewelry applications, including bungee! The metal springs each measure 3/8th inch (9.5 mm) long, and each pair includes a mini lobster claw closure (which is about 1/2 inch or 12.7 mm long). This fastener requires some crimping (use jewelry pliers - not included) to complete the assembly, so adult supervision may be required. One strand of Bunjee brand bungee craft cord (or any cord 2mm-4mm in thickness) can squeeze into the base. Illustrated assembly instructions are included under the header card.