See PDF link for more information. The J5510 series has 2 rotary cleaning arms and a fibreglass body; it is designed to hover (no wheels) for cleaning rough surfaces like rooftops or rock beds. The J5515-24SS is made of stainless steel, has 3 rotary cleaning arms, and non-marking castors. All models have a maximum flow of 8 GPM and weights vary from 32-45 lbs. Replacement parts available (ie. J5515R01-20 thru J5515Rxx-20). During operation, should you experience a buildup of small stones or other foreign material within the cover, we recommend that you simply tip the cleaner on its side at 45 degrees, expel any foreign materials. This will give longer life to your tips, swivel arm, nozzles, and brush skirt. The tips that have been installed on your surface cleaning system permit the use of your cleaner with a pressure washer producing up to 7 GPM at 4000 PSI. Periodically check the tips to ensure they are not clogged by dirt or other matter as this can cause the rotary arm to stop spinning, leading to missed areas on the surface being cleaned. Please ensure that the nylon brush skirt remains in contact with the surface being cleaned. Do not operate on overhead surfaces. We strongly recommend that safety goggles, gloves, and work boots be worn when operating a Whirl-a-Way.