With proper care and maintenance your bushings should last for years. Keep out of extreme heat or cold for maximum longevity.
If you need to replace for any reason this bushing will make your Surf Adapter ride good as new. Durois a measure of hardness, the harder the bushing the more resistance it will give you. Consider that lighter riders will likely prefer softer bushings and heavier riders will prefer harder bushings.
90a is the softest bushing. Best for skilled riders or youth who enjoy a very loose turn radius.
92.5a is quite soft. Suitable for people who love an extremely loose feeling, or youth riders.
95a is standard. It's a happy medium and leans toward the looser side at low speeds. Allowing for high performance maneuverability.
97.5a is a firmer bushing for riders looking for extra low speed stability.
100a is a very hard bushing. It will stiffen up the Surf Adapter significantly at all speeds. Making it more of a cruiser.