Output Board with 3 relays for connecting devices (spindle, cooling, …). 0-10V output for VFD (spindle speed). Everything is optoisolated! Works with all Planet CNC Controller versions. Compatible with the following CNC USB Controllers: CNC USB Controller Mk3 ( 4 ) axis CNC USB controller Mk3 ( 9 ) axis CNC USB controller Mk3ECO ( 4 ) axis CNC USB controller Mk3DRV ( 4 ) axis