The ability to keep gunk out of your marker
The reason for me purchasing this product was to keep stuff out of my Tippmann. I was at the annual Ontario, Oregon D-Day tournement, sitting in the resurrection point, and I dropped my Tippy (on accident) right in the dirt. The dirt seemed to target my open bolt! The gun filled with dirt and I had to get out of the field (which got me shot several times) and kleen out my marker.
This product dose exactly what I bought it for. Its a good product. I recommend it.