Inside cable for Foredom SR motors This 39" long inner shaft comes installed and should be used to replace broken or worn shafts on these motors: M.SR, M.SRM, M.SRB M.TX, M.TXM, M.TXB M.LX, M.LXM, M.LXB M.PGX Use with outer sheaths S-77 or S-77N sold separately.