Castle Nut Driver for Aprilia RS125 Diagnosis & Measurement It is a very easy

It is a very easy way to ensure that all the floats in a multi cylinder engine are all at the same height to prevent lumpy running

insert one of these screwdrivers into the head and give the top of the screwdriver a good sharp tap with a hammer and you'll find that you should be able to undo it

soldering etc

though we have never found the need to alter the factory setting on ours

Castle Nut Driver for Aprilia RS125 Diagnosis & Measurement It is a very easyCastle nut socket for Aprilia RS125 swinging arm. This socket can be driven by either a 19mm socket or spanner. Made from medium carbon steel, heat treated and chrome plated Dimensions: External Diameter 30mm, Internal diameter 24. 5, Lugs 4mm x 5mm x 4off