Tapmedic Handle Seelves

Most cartridges have what we term a ‘handle shoulder’. Its function to to stop a handle with splines running all the way through it dropping down the spindle.
Despite its existence on most, many handles have an in-built ‘stop’ so do not need this external shoulder.
The test to determine whether you need to replicate the shoulder or not, is to try the spindle in the handle. If the spindle goes all the way through then you need a shoulder. If not, then save some money and do not fit one. 

To replicate the shoulder, you can use either the pre-sized sleeves supplied, or you can make custom sizes using the 120mm length of sleeving and the cutting jig.

See the image for how to mark the handle shoulder position accurately. 1mm higher up the splines (making it longer) is normally acceptable, but cut it any shorter and it may bind.