Micro Natty, 1/10th the size of NG contract.
Note that this is financially settled so its really 1/10th of HH which is financial settle and not NG which is physical delivery.
There is a small spread between HH and NG, with NG nearly always at a premium of 3-15 ticks.

https://www.cmegroup.com/markets/energy/natural-gas/micro-henry-hub-natural-gas.html

Actually these are penultimate settle (ie settle financially the day before NG does) so these are actually 1/10th of HP not HH.

The spread between NG and HP is normally only a tick, unlike NG and HH.