here is no abrasion on the shaft in spite of long use with its hard-plated, no leak with a special Teflon and O-ring.
Also there is no drip the remaining liquid after shot because of choosing the SNUFF-BACK type.

here is no resin infiltration into air-working part due to completely separated Air-working and Resin-Flowing.
Simple in construction, no hardening in the flow working room because there is no room to make resin stop
(Most proper for Dispensing Urethane)