Bushings need to be replaced in your skateboard trucks every once in a while, because they break down and stop giving good feedback and springiness. The bushings cushion the truck when it turns. The stiffer the bushings, the more resistant the skateboard is to turning. The softer the bushings, the easier it is to turn.Popular Bushigns are Bones or Khiro and they sell a range from Hard to Soft. Soft being around 85A and Hard being around 95A, but Brands like Khiro sells a MUCH larger range going to extra soft/hard.