Highly saturated nitrile butyl rubber works with R12 and R134a. Molded storage case included. Assortment contains: (20) 7/32" x 1/16", (20) 1/4" x 1/16", (20) 6.8 x 1.9, (20) 5/16" x 1/16", (20) 7.8 x 1.9, (20) 8 x 2, (20) 8.8 x 1.9, (15) 7/16" x 1/16", (15) 7/16" x 3/32", (15) 11 x 2, (15) 12 x 2, (10) 13.9 x 1.8, (10) 9/16" x 3/32", (10) 14 x 2, (10) 15 x 2, (10) 17 x 2, (10) 11/16" x 1/16", (15) 11/16" x 1/8".