The Retainer is a different approach at Restoring/Retaining

DTR retaining

The retainer sits on top of the glans and the shaft skin is pulled up and held in place by a gripper.

Retaining with weight
Retaining with Air
DTR retainer sizes
Notched Retainer
Foreskin retainer  with notch

The bottom of the retainer is about 10 mm deep. This is about half the depth of a DTR bell.

Retainer spacer
Threaded retainer
Foreskin retainers  solid

Solid Retainer :
Uses: Retaining , Moisture retaining

Uses: Retaining

I found the Retainer to be a very useful device. It was able to hold on and not fall off the way O-rings can when you dont have much skin to work with. I did use it for Direct AIR and Weight when I was using those methods vs the DTR bell because it was a little more compact. I was able to sleep with the retainer in place however I would advise not to do this unless you have enough skin to work with and are comfortable doing so. Personally I feel an O-rings or the keeper are safer for sleeping and retaining.