These little things are the STANDARD RUBBER BUSHINGS that are used in the TRAMPA Skate Trucks. When fitted correctly they allow the metal parts to move around without rubbing against each other, supplying the necessary amount of movement that we then control with these rubbers & special dome shaped Washers which when assembled creates us the steering. By changing the rubber hardness in the Skate Truck Bushing, will change the characteristics & steering performance of the Deck. Rubber hardness is measured in Shore Durometer resistance, These Skate Bushings are 95a rubber hardness, which gives an ideal range of steering for most beginners to intermediate riders.
If you Screw the 3/8ths if an inch Nut down onto the Kingpin, this will squash the rubber & increase the tightness of the steering resistance. An Oversized Washer encourages the rubber bushing not to split under tension, but due to the harsh environments & tension these rubbers operate within, over time they will perish, possibly split & ultimately needing replacing. Stiffer rubbers can be purchased if you cant get tight enough with these.