Seamax Easy Load Boat Launching Dolly 12&rdquo; Wheels System for Zodiac Type Inflatable Boats & Aluminum Boats Seamax Easy Load Boat Launching Wheels Set is designed by Seamax Canada, made by hardest marine grade T6 aluminum alloy with CNC processing; Shiny looking anodized coating on all aluminum parts, product is good for saltwater using; Small parts are all made by solid stainless steel. Lab 1000Lbs tested, support MAX 500Lbs loading in all condition, good for inflatable boats, aluminum boats and fiberglass boats. This system is designed for boats with transom, the length of the boat should not exceed16 FT & total weight within 500 Lbs. These transom wheels should only be installed by an adult with some experience in working with tools. To install the wheel set properly, you will need to drill 4 holes (5/16) in the transom for the mounting. Addition reinforcement may be required on some aluminum transom. And you can use marine sealant and suggested Sikaflex 291. Benefit from its new Push Button design & max 3 stages wheel arm, the system can be adjusted while afloat in the boat leaving or coming into, it can also bring different performance position for boat launching. The wheel arm length increment is 2.5 per stage, plus the wheels diameter, the range of length is 22-28 inches. Tire inflation: Dolly tires may not be fully inflated when shipping; please only give 15-20 PSI pressure at room temperature before using. Best to use portable type digital air pump in case tire over inflated. Tire over inflated will cause damage and the warranty is not covered. Dual wheel kit is available for this dolly for heavy loading application. Maintenance: Wash it after using from salt water or sandy beach. Check tire pressure before every using. Dont store the wheels under the sun or beside the heat to maximize its life time. Take the wheel arm off from the transom bracket when store your boat. Lube the spring load dolly system is necessary. Keep the lock pin on the dolly bracket. Manufacturer 2 years Parts Limited Warranty within USA & Canada. 30 days free replacement on any defective ransom wheel sets.