Weck Xtra Small - Pack of 10 ( fits WK756) - $6.65 Small - Pack of 10 - $4.95 Medium - Pack of 10 - $5.95 Large - Pack of 10 - $6.95 Xtra Large - pack of 10 (fits WK750) - $7.95 Qty. 1 2 3 4 5 6 7 8 9 10 Add to Cart is currently backordered. You may still purchase it now but it won't ship until it becomes available again. These WECK rubber rings are essential when using WECK jars for preserving. Please check each jar listing to determine which size ring is required. NB: rings are used in conjunction with the clamps