150 pc. Nylon Insert Lock Nut Set (Jam Nuts) * Nylon insert locknuts ("jam nuts") come in six common sizes. * Includes: 25 - #10 x 24, 35 - 1/4" x 20, 25 - 1/4" x 28, 30 - 5/16" x 18, 25 - 3/8" x 16, 10 - 1/2" x 13. * Very handy for many applications. * Set is complete with plastic divided storage case.