The Hiblow 40PC000031P Rebuild Kit will restore your HP-30 or HP-40 air pump back to working order in under 20 minutes. Air pumps have diaphragms that slowly wear out over time and must be replaced. So make sure that your air pump remains functional with this diaphragm kit. The HP-30 & HP-40 air pumps contain two diaphragms. This repair kit comes with everything you need for a full rebuild including: new diaphragms, casing blocks, and a replacement filter. The only tools needed for repair are: #2 Phillips Screwdriver, Straight handle 7mm nut driver, Straight handle 8mm nut driver and a Rubber Mallet. Do not use power tools because they can over-torque the screw or nut and cause damage.