GLOGLOW Cooling Vest, Welding Steel Air Compressed Cooling Vest Vortex Tube Air Conditioner Waistcoat Cooling Cold Vest Air Ice for Heat Relief

Q: what does the part in the middle do? The other ones that look like this one doesn’t have that.

It absorbs moisture. It's got like a small cork in it to keep from blowing water thru the tube in the vest. Not like it'd b alot of water but how air hoses blow a small midst sometimes. This eliminates that. ALSO besides blowing air thru the tube in in vest, the orange cap on the blue piece opens to blow a steady stream of air!! It really is an awesome thing to have. I LOVE mine!!!