Military Army Therm-a-rest Self Inflating Camping Backpacking Sleeping Mat Pad
OD Green. Tested. 
NO LEAKS!
May have stains, etc from previous military use. 
Come in batches from neat and clean to used/dusty/water stains, etc. 
No cuts or tears.
Weight 2lb

Does not 'auto inflate'. 
Takes a few puffs of air to fully inflate.

There is an alternate version (discounted) of this by a separate manufacturer.
Material and blow-up nozzle are slightly different. 
https://www.ebay.com/itm/235326564009