Internal relief valve protects circuit components, air inlet filter protects motor . High pressure output, light weight by Aluminum Alloy reservoir. Serviceable pump motor is not a "throw away", providing economical repair. Permanently vented reservoir cap. Three-position treadle provides cylinder advance, hold and retract operation. Equipped with air coupler, easy for using. dBA 85 at 700bar for all SPA-6 pumps, lower noise.