If you are tired of your PCP fill probe getting dirty, you can protect it with one of our yellow push on caps.  This cap covers the probe just past the bottom O-ring on my Hatsan probe.  This is what I use and it holds up great.  I discontinued the black EPDM rubber one I used to sell because it stretched and got loose over time.  This yellow one works great and has stayed snug for almost six month now.

The inside height is 20mm and it will fit a probe that is 8-9mm thick.  It should fit many of the fill probe brands on the market and what you want to confirm is the diameter of your probe and that the bottom O-ring is within 20mm from the end of the probe so the cap can cover it.

Pricing is for one yellow pull-tab cap.  

Fill probes shown are for comparison and are not included.