I used this mug press on 12 15oz coffee mugs with printing on one side. The press worked pretty well once I tweaked the mug placement. I then used it to print 8 11oz mugs with printing on both sides and am really disappointed. I tightened the screws prior to placing the first mug in, and one side of the heating element does not adequately heat in order to get the colors to print vibrantly. I tried further tightening the screws and no luck. It wasn't stupidly expensive, but I would think it would work consistently for more than 20 total mugs. In addition, the interior part of the mug press bubbled toward the edges and there are times (inconsistently) when there was a bit of smoke coming from the back of the mug press.