Hi Doug,
Have a look at this thread on CN about this subject, the consensus is it works great for sealed tubes like SCT's or Mak's but not so good for Newts.
They found the reflectix insulation the best for stopping the OTA from cooling down too quick.
https://www.cloudynights.com/topic/6...acket-for-mak/
Picture attached from Richard O'Neill
Cheers
Bill