yeah thats right. all you would know is that it has some compression which doesnt really help. think of it this way a bicycle pump can blow your finger off the hole. but thats only like after 15 psi. but you need like 25-35 psi to fill a tire up. now compression in a cylinder is high too and having it blow your finger off isnt saying much. kinda like testing the strength of a gun by seeing if it shoots through paper. get what i mean?