Linear motion, wheels vs bearing, what is the big deal?

Single Flange Long Standard Linear Bearing for 1 wide extrusions t slot bearing Product Information Weight, 0,0054 kg Bearing type T Slot Nut Material Galvanised Steel Thread Size M6 T-Bolt Length 20 Bolt Head Thickness the bounty hunter slot The T-slot insert linear bearing pad is commonly used with bearings to create linear motion and is made of self-lubricating white UHMW It has a low coefficient

tsa slot code vergeten T-slotted aluminum bearing with brake holes made for the 15 series Measures tall x wide x 6long Rides on the side of a 15 Series extrusion