Come as a set of two trucks - the colour of the bushings vary but are all medium hardness.
Size 4.25 has a 6.8" wide axle - fitting decks of 6.25" up to 7.6".
Size 5.0 has a 7.6" wide axle - fitting decks of 7.5" up to 7.875".
Size 5.25 has a 8.0" axle - fitting decks of 7.875" up to 8.25".
Size 5.5 has a 8.375" axle - fittings decks of 8.25" up to 8.6".
Size 6.0 has a 8.75" axle - fitting decks of 8.6" up to 9.0".
Size 6.5 has a 9.0" axle - fitting decks of 9" and up.