Split rings are made of a double coil of wire like a miniature key ring. They are a very secure way of linking jewellery components together as they cannot come open like an unsoldered jump ring can.

Jewellery Making Starter Kit (Red and Black)
A Starter Kit for Jewellery Making that includes full instructions, jewellery tools and enough beads and findings to make, 2 Strung Necklaces, 2 Bracelets, 5 pairs of Earrings and 1 Wirework Link Bracelet.
Split rings are made of a double coil of wire like a miniature key ring. They are a very secure way of linking jewellery components together as they cannot come open like an unsoldered jump ring can.