If you are replacing the leather washer in your pre-2008 SILCA Pista or SuperPista pump, you might consider also using this updated washer, nut and spacer kit. The main concern with continuing to re-use your old nylon-inserted nut is that it can lead to loosening of the assembly later on as the nylon insert will take a set over time whereas a new bolt kit guarantees years and years of trouble free service ahead. This kit uses only nuts, washers and spacers from a factory in Ohio especially chosen for their high quality product, awe-inspiring environmental policies and their ultra-low energy galvanizing processes.