Hydraulic or pneumatic

I am actually uncertain myself, but please give me a little more time as I get confirmation. I hope to get back to you as soon as I have word.

Hey there, I hope I can help. The 40-015 is a pneumatic type door closer used on heavier storm doors or the steel security-type storm doors. It has a torsion bar which adds to the strength when closing the door.

I'd be happy to assist with any follow-up questions you may have about this product.