Frixa brake pads are a UK designed quality performance pad designed with passion to create a long lasting, more advanced replacement for the genuine, often cheaply made brake pad. Available in soft, medium and hard. Choose soft for cold, wet or winter conditions up to around 10c. Medium is suitable for temperatures of 10-20c with hard being designed for them really hot UK summer days or high temperature countries. The BS5 system is the pre Racer 401s (2017) OTK kart, so anything from 2004 including EVRR, EVR, EVK, Racer 401. The BSD is the Racer 401s brake system, as well as being used on KZ karts.