The 4in x 5in T-Bar is actually made out of two 4.5in pieces of aluminum tubing. One of them is mitered and welded into the other, giving a full height of just over 5in. Because the weld takes up room on the other tube, we round it out and call it about 4in long. Instead of offering up a "4.28in x 4.5in (But Also There's A Weld) T-Bar," we shortened the name to lessen the mouthful, saving you time to mount your accessories and ride while the weather's still nice.
Clamp not included.
Also available as part of the "Bar End Shifter Mount" if you would like the T-bar with clamp included.