18" arbor extension. For use with Lenox bi-metal hole saws (Lenox model No. 1L, 2L, 3L, and Lenox Leader wood bits model No. LL100 thru LL256). Chuck size 1/2". Chuck Size: 1/2", Length: 18", Fits Model: Lenox 1L,2L,3L & Lenox Bits #LL100,LL256