The UP leg cover can be used in conjunction with most UP harness models and can also be used with harnesses from other manufacturers. For minimal wind resistance and warm legs. The High Speed comes in two sizes, M and L, and with or without integrated front reserve container. If you wish to combine the High Speed with a harness where the reserve pocket is under the seat plate you will want to use the one with the integrated front reserve container, as the High Speed leg cover will completely cover the seat-mounted reserve.