Router table miter slot, who uses them?

Router Table Miter Slot Track or T-track? miter slot track Rockler 36'' Miter Track - Miter Slot Fits 1 x 12 Deep Dado & Accepts a Standard 34 x 38 Miter Bar miter slot runners track Woodworking T-slot Miter Track Jig Fixture Router Table Alloy 400mm Socket Set at best prices with FREE shipping & cash on delivery Only Genuine

miter slot bar Hi - I am looking to add a t-track to my cross cut sledge However, when looking i can buy a mitre slot and t-track slot