I have one of these for both the 18" Obsession and the 14" SDM. They are excellent for protecting your scope once set up for a star party.
Something else to consider is the Astrosystems Transport case. This is an exceptional quality product and extremely heavy duty and well padded internally. It is excellent for protecting the scope while it is being transported but it is also excellent to keep dust and crud off and out of the scope while it is being stored in the garage.
About 1/2 way down this page, not cheap but exceptional quality.
http://www.astrosystems.biz/covers.htm
Cheers,
John B