It works great with GT2 48 Tooth Pulley for 9mm Belt.
The idler wheel has 2pcs 698ZZ Ball Bearings. It has a 10mm width flat area with dual flanges for Timing Belts.
It can be used as Idler for up to 9mm width Timing Belts.
Inner Bore: 8mm
Outer Diameter: 41mm
Height: 19mm, 10mm width for belt.