This is the KEELA under Body Combat shirt (UBACS) which is a non-hindering tactical shirt functionally worn both with or without Body Armour. 

Key features of this fantastic product - 

• Torso is made with FR Jersey knit fabric that wicks away moisture and keeps you cool. 
• Mil-spec Extreme NYCO 65/63 RIPSTOP sleeves.
• Low profile three quarter zip to enable easy venting, plus easing wearers thermal load or rubbing of Body Armour around neck.
• Comfort placket behind YKK zipper.
• Low profile double layer pocket on the bicep.
• Flexible velcro IFF Panel.
• IFF velcro glint square patch on each upper arm for identification. 
• Low contoured elbow pad configuration to enable the use of elbow pads (sold separately) 
• Gusseted cuffs.