The following excerpt is from "Extreme Rocketry". The intention is to allow guests to get a basic feeling about a kit. We strongly suggest that you get a copy of the referenced Extreme Rocketry and read the entire article. Inside you will find many helpful hints in construction as well as other useful information. For more information, use the link above.

• "One of the favorite rockets in my collection has a classic 54mm Slimline Motor Retainer installed. It is reliable and easy to use, but I had always thought the design would be slightly better if it used some kind of threaded retention."
• "It's as if someone read my mind, because Slimline Motor Retainers now come in a threaded version, in sizes from 29mm to 98mm."
• "There are other really good threaded retainer systems available but these units have an external closure ring."
• "... the external design creates more drag, ...."
• "The threaded Slimline is comprised of three components:"
• "A base, a threaded ring, and an extraction tool (not completely necessary, but makes life simpler)."
• "The base glues to your motor tube (you'll need about 1/2" of motor tube sticking out."
• "Then insert your motor and secure with the ring. That's it."
• "I recommend a nice money saving option if you plan to outfit more than one rocket; buy the "starter set" for your first rocket, then buy only a base for each additional rocket."

The Slimline Retainer has been around for quite some time. Based on this review it sounds like the product has just gotten better. The only con listed was that there are cheaper retainer systems available if you don't need a minimum diameter system.