A quick release coupling helps when technical devices such as external filters need to be disconnected from aquarium-mounted hoses for cleaning To assemble: cut through the hose, attach the hose ends to the quick release coupling and secure from slipping with lock nuts Freshwater and marine water resistant, extremely robust POM ABS plastic. Not designed for tap water pressure (4 bar) The full water flow is maintained. No reduction in performance when used on technical equipment Package contents: 1 quick release coupling with stopcocks