Spring Air Retracts are made by Spring Air, they are made in Melbourne, FL.
To restrict the air you can also put a wheel collar on the air line and tighten the screw, till you get the speed that you want. Below is the Contact info for Spring Air, and they are super nice and can answer all your questions.
Josh
http://www.retracts.com/
Phone: 321-728-9002
Fax: 321-728-2881