TBB002 SILVA no. 071/072 machine quality cobalt taps, BSA. HSS+CO B.B. shell tap 34.85mm - 24tpi (1-3/8"x24tpi) British right/left hand thread), six flute with 16mm. through bore and 20mm. length with keyway. These taps are designed for the Marchetti Bottom Bracket tapping machines, but work beautifully with the new LAN71 manual tap holders which are now available (go to b.b. tap/face section). $410.00/pr. To order, please contact Andy. PayPal and good check accepted.