USGI Level 2 Grid Fleece Thermal Undershirt

The US Army saw all the great gear the USMC was getting in the 2010's and said "This is the FROG thermal shirt we have at home."

It's basically the same thing as our favorite long sleeve, but fits true to size where the USMC FROG shirts were hella stretchy and oversized.  Part of the ECWCS program, the Level 2 Grid Fleece shirt is meant to be worn as a second, warming layer, between your base layer and waterproofing/cold weather shell.  

We love these shirts as a cool weather PT shirt, as a warming layer.  Just great stuff.  Quick drying, and comfy.  These won't last long, got a small batch from one of our local sources.