Sold as two bushings, large cup washers, and a sticker.

APS stands for Animated Polymer System.  This urethane is very lively giving you more turn that a same durometer stock bushing, with lots of rebound.  APS doesn’t compress the same as stock bushings and other formulations, so you can take it from the standard just snug washers to a few full turns without effecting the compression and decompression characteristics.

The Street Barrel is the size of street bushing usually found on the board side of the trucks.  The Street Barrel just like it's reverse kingpin Barrel cousin is the average break from center and return to center bushings.