A friend of Mine bought this for me back in January. Dont let the sticker fool you! It says “1/4 in Port” But the port actually is 1/2 inch port! The best part of this? Its light and its 7 gallons! 
Tell me what you think! I am going to use this on my bicycle trailer when I get all healed up, instead of the heavy oven 4 gallon dual steel air tanks. A Little bit lighter. 
here is the gage on it.
Mate awesome. How much did he pay for it.
It was on sale at Harbor Freight, about $50.00. 
As long as there is a port on the bottom for it for a drain, you should be good!
That should be easier to tote around.
FYI - 1/4" pipe is .54" O.D., so yeah, the inside of that port probably measures close to 1/2". If it was truly 1/2" NPT, it would measure about 13/16"…
thanks everyone! To angie, there is no port of the bottom of the tank, its not a problem since I will once in a while tip the tank upside down and open a valve thats on top of all the T Fitting I put on it to drain the tank.
As long as there is some way to drain it, you should be good!!