I recently purchased and carried with the UnderTech tank top. Although it does everything it says it does, but is not overly comfortable. I found the holster pushes the pistol grip (Kimber Ultra Carry II) outward pressing against my bicep and is actually painful at times. It is slightly better with a smaller frame auto (S&W Bodyguard) but still you always know it is there. This feel/rub may be reduced with a full t-shirt rather than the tank top. With fixed holsters on both sides the UnderTech is a better designed shirt that the "Packin' Tee" and will carry a heavy midsize auto (S&W 639 stainless) without sagging. Overall, though the most comfortable has been the "5.11 Tactical Tee", but the pocket opening can be identified at the front of an over shirt and the price is higher. For a small auto or revolver in a good concealed carry the Undertech does what it says it'll do. Good gear for a good price.
Pros: Cost, left/right/dual carry
Cons: pistol grip pushes outward, rides back further than shoulder rig
This review was written in the old system and had content requirements that are different than reviews written today.