3/8, 8mm and 7mm pot caps with holes on the side to inject cleaner through a spray straw. As the threads are fine, use care when threading the first time. 3/8-32, 8mm-.75 and 7mm-.75. Three with caps and three through so you can use your finger as a cap and feel the sprayey goodness. Screw onto potentiometer and spray through small hole on the side.