The Ratchet LN upgrade kit enables the conversion of DT Swiss 3-pawl hubs to the renowned DT Ratchet freehub system Pawl freehub systems create relatively small engagement surfaces, which result in higher stress on the contact area. The Ratchet System is extremely reliable due to the simultaneous engagement of the ratchet faces, distributing the force evenly over a large area DT are the original ratchet hub innovators, with over 25 years of development and refinement behind it no other manufacturer has matched DT's system for ease of service, reliability and durability Tool-free servicing concept make maintenance quick and simple, even mid-ride in a pinch LN system is specific to 370 hubs (such as those found on 1900 series DT complete wheels), the freehubs are not compatible with standard Ratchet or Ratchet EXP hubs Requires both a HBDT835 Ratchet ring nut tool and an HBDT5266 Pawl ringnut tool to install, DT recommends that this work is carried out by a qualified mechanic