These 2+2 raised panel cutters are designed for 5/8" thick panels. All 1-1/4" bore cutters can be used with back-cutters UP230 and UP231 when using 3/4" stock. All 3/4" bore cutters can be used with back-cutters UC230 and UC231 when using with 3/4" stock. These 2+2 raised panel cutters are designed for 5/8" thick panels. All 1-1/4" bore cutters can be used with back-cutters UP230 and UP231 when using 3/4" stock. All 3/4" bore cutters can be used with back-cutters UC230 and UC231 when using with 3/4" stock.