A Hot Tub Diverter Kit is a device that helps to divert water from the main pump to different jet and air flow systems in a hot tub. It helps to control the amount and direction of water flow within the hot tub. You are buying a gray notched 3 3/4" spa diverter cap, handle knob, stem o-rings only. this is a NON Buttress style cap. This diverter cap mounts on top of the diverter valve with the stem sticking through the (2) small O-Rings then the handle goes in top of the stem square the large o-ring fits on the body under the cap. the diverter valve that this part fits is used to divert water into different sides of a hot tub and fits many different brands. The outside measurement of the Cap is about 3 3/4" the inside thread measurement is about 2 3/4" and the center hole where the stem and o-rings go measures about 3/4", Then the handle is about 4" long end to end and 2" wide side to side at the widest part and the square hole in handle is 7/16" wide. the stem fits into the valve body the stem is 5 7/16" long and the widest part is 2 1/4" wide and the square part on the top that the handle fits on is 7/16" wide. ?? Plumbing is measured by inside diameter because this measurement is used to calculate the size of the pipe. The inside diameter measurement is the distance from one side of the pipe's inner wall to the other. This measurement is important because when purchasing fittings such as elbows and couplings, the inside diameter is used to ensure that the correct size is selected. A hot tub diverter stem is a component of a hot tub that diverts water from one side of the tub to the other. It is usually attached to the side of the hot tub and actuated by a valve handle. The diverter stem is connected to the hot tub's plumbing and helps control the flow of water between the hot tub's jets and other outlets. A hot tub diverter handle is a device that controls the flow of water from the hot tub's pump to its jets. It is usually a plastic handle, that can be turned to open or close the water flow. This allows the user to direct the water flow to different parts of the tub. A hot tub diverter cap (also referred to as a "spa diverter cap") is a plastic, circular cap that fits over the diverter valve on a hot tub. It prevents debris from entering the diverter valve, while still allowing the air to flow freely. A hot tub diverter o-ring is a circular rubber seal used to create a water-tight connection between the diverter valve and the plumbing pipe. It is usually found in the suction and return plumbing lines of the hot tub. The o-ring helps to reduce the possibility of water leaking from the valve and can also help to improve the efficiency of the hot tub's circulation system. Fits Most Standard 2" Diverter Valves Please message me with any questions and checkout my other auctions. Thank you!