Seat tube reamer SILVA no.378 R/H spiral flute interchangeable 31.6 diameter, 60mm length, slot 4.5w x 5.5d, taper 3 degrees x 10mm, 14mm bore. NOTE: All interchangeable seat tube reamers have a 14mm bore and mate up to the arbor no. STM009 turned shaft o.d. of 14mm - one arbor works for all interchangeable reamers.