Thermostat 833072003 is for select Mercury Optimax, 2.5L, non-Pro, V-6 outboards (s/n 1B227000 and above). It is a 143 F degree thermostat. Thermostat only. Additional seals or gaskets may be required. See your owner’s manual or service manual for more information. The Quicksilver brand has been the marine industry leader in delivering premium engine lubricants, accessories and original equipment replacement parts for more than 65 years. It applies the same quality standards as a supplier of lubricants and replacement parts for many original equipment brands in the powersports industries. Quicksilver has earned a loyal following by providing the highest quality products, validated through some of the most rigorous environments and testing procedures. No aftermarket company comes close to matching the level of research and design that goes into Quicksilver products. Buying Quicksilver is buying performance, protection and peace of mind.