4Pcs 6X30X13mm Plastic Coated Sealed Bearings Steel 606ZZ Deep U Groove Guide Pulley Rail Ball Rolling Bearing Wheel
https://www.vogueparade.com/shopping/EN/42/1/1005003638033759/4pcs-6x30x13mm-plastic-coated-sealed-bearings-steel-606zz-deep-u-groove-guide-pulley-rail-ball-rolling-bearing-wheel//