Seamless construction, non-chaffing, strategic venting. Sweat-wicking fabric is 4-way stretch. Fabric inhibits the growth of odor-causing bacteria on the shirt.
Why pay $68 for a T-shirt? Because you'll still be training in it years from now. I bought my first Metal Vent shirt 7 years ago, and after wearing it a couple times per week and washing it hundreds of times, it still looks the same and keeps its shape. The color never seems to fade and the collar never gets stretched out.
The fit is perfect too. Not too clingy, but fitted around the arms so people will definitely know you lift. Lots of colors available too. – Chris Shugart