Zirconia 2" Blue Cloth Quick Change Disc (2-P24, 2-P36, 1-P50) Retail Pack R 2QC-Z-KIT-R5 Starcke #: R 2QC-Z-KIT-R5. Premium Blue Zirconia grain on heavy duty cloth backing for sharper cutting power and longer lasting performance. Type R Male Roll-on connection.. Exceptional results in grinding applications in metal, autobody, marine and fiberglass.. Max RPM 30,000.. Professional grade, German quality.. Stocked & shipped from the US. Starcke is family owned with over 100 years of experience in manufacturing abrasives. 2QC-Z-KIT-R5