These clamps are part of the WECK canning system, they are for use with all Weck jars. Weck clamps are reusable. For storage 2 clamps are adequate, for preserving 3 clamps are recommended.
Note: these are sold individually, the price is for one only clamp.
Read Weck’s Tips & Tricks to Preserving Blog for everything you need to know before you get preserving at home