SEAMAX Deluxe 4 by 4 Boat Launching Wheels System for Zodiac Type Inflatable Boats and Aluminum Boats The Deluxe Boat dolly is with well 3D design. Made of the strongest marine grade T6 aluminum alloy with CNC processing. Shiny looking anodized coating on all aluminum parts. Good for saltwater using. Small parts are all made by solid stainless steel. 16-in air filled tire lab 1000Lbs tested, support MAX 600Lbs loading in all condition, good for inflatable boats, aluminum boats and fiberglass boats. Benefit from its new design - 4 stages of length & 4 wheel arm position, the dolly can be adjusted while afloat in the boat leaving or coming into, the dolly system 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 23-30 inches. The wheel arm can have 60 or 90 degree locking position up and down. Free up more space on the top and side of the transom. Lower 60 degree position can let the wheels run at the same level as the prop; the result is to turn the dolly as your prop guard when at rocky beach. The transom bracket installation area is about 8x3 inches, shorter transom bracket design can give more possibility of installation for all type of boats with different transom. User can install the brackets at water line top position, so the water wont hit the screw holes. Two bottom collinear bolts give the bracket extra strength and stabilizes. Triple heavy duty, triple quality! Product made by Seamax Canada with 2 years limited warranty. The Quick Operation Features of Deluxe Boat Dolly include: Spring load locking pin for wheel arm position adjustment; Solid spring load buttons for wheel arm length adjustment; Quick released lock pin for wheel arm and wheel bearing. 100% Customer Satisfied Guarantee!