uf is the measurement microfarad. Capacitors basically store electrical current and in the case of an RC application release it quickly when a path to ground (ie neg batt) is made availible by nailing the throttle. It improves punch in stock 19t by allowing a rapid release of amperage to the motor, but is also useful in all forms of rc because it helps to reduce emf related intereference caused by the high current components of an rc car. The schoktty diode (like all diodes) only allows current to flow in 1 direction. When you apply the brakes current flows back into the speedo from the motor and can damage the breaking fets if it is too high, or in the case of some speedos virtually any reverse current is damaging (the KO's come to mind). The link posted previously is awesome and really overkill (in a good way!). + I am sure buying it from an electrical supply distributor like newark or mouser will cost a lot less than comprable KO ultimate schokkty which costs $40!