This is taken from the Highland Hardware web site on a page about their replacement totes and knobs:
I have never heard nor seen a t-shaped handle and am curious what it would/should look like. I have just acquired a Stanley Bailey #5 jack plane in very rough shape and also another that is a 14" long Millers Falls in poor shape. I don't have the money to spend $30.00 on a $7.00 plane to get new knob and tote so I thought I might make my own but am interested in this t-shape. Anybody know of it?
Our rosewood front knob is pretty much the standard turned shape. A sculpted T-shaped handle would better match the shape of your hand, but it would be difficult to mass produce economically in wood, so we’ve settled for a nicely shaped version of the ordinary round knob. Our rear handle is modeled on a couple of our favorites here at the store, handles which we’ve modified through trial and error until they fit the way we want them to.