Best used on ferrous and nonferrous metals where initial price point is most important|Designed for softer metals where standard discs can gouge and for contour grinding of structural pieces|Type TP/I fit snap-on/snap-off plastic attachment system|All QC cloth discs are designed to run on back-up pads that are rated at or above the RPM of the grinder|When using back up pads for FlexEdge discs, use one size smaller than the disc