A well-functioning (and nonsmelling!) marine head is an essential part of enjoying time aboard any boat, especially a cruising sailboat. It's also important to be able to repair it easily if it clogs or something breaks. The Jabsco Twist 'n' Lock Marine Toilet (manual pump) is currently the least expensive model available and it does an excellent job - replacement parts and service kits are readily available is anything goes wrong. This is the replacement Twist "n" Lock Pump Assembly sold as a complete unit with Joker Valve gasket for you to simply swap over when your existing pump has seen better days.