Welcome! Our high quality "SUPER SUN" 4-gallon professional backpack sprayers are known world wide and made for the professional user...built for lifetime service. Both models use the same parts except for the pump assemblies. The AP-25 (piston pump) has a maximum pressure of 90 P.S.I., while the AP-30 (diaphragm pump) has a 70 P.S.I. Both are made of P.E. plastic and weigh less than 10 pounds each. They are made to fit comfortably to the user's back with no fatigue. For more information on the AP-25, click here or on the picture below. For more information on the AP-30, click here or click on the picture below! You have reached the right website if you are looking for Sun sprayers products, lawn and garden sprayers, professional hand spreaders or products for professional weed control. ** If you have come to this website in need of parts for either the AP-25 or the AP-30, use this link to enter the retail parts list and service bulletin information pages. Note : AP-25 parts interchange with SUN AP-16, SUN AP-20, Gilmour KP-400, and Ames 21-960. We also offer the AP-2 Automatic Compression Sprayer. The Sun AP-2 is portable, automatic, air-compressed and hand operated. It's multi-purposes include garden spraying-weed and pest control, liquid fertilizing, window-glass cleaning, wallpaper removing, vehicle maintenance, and many other applications. Click here for more information on the Sun AP-2.   www.sunsprayers.com