4" Flatties Round Mirror Head (STANDARD VIEW): Flatties mirrors are 10-24 thread and compatible with all the Fatties line of accessories (you can use any arm, mounting post or adaptor). As our customers demand, Flatties carries over the Fatties features you expect in a top quality mirror: billet aluminum construction, show quality finish, smooth pivot points and vibration elimination construction. NOTE: For expanded view mirrors please look at our Fatties line of extended view mirrors.