Casström's No.3 Dangler is an excellent upgrade that allows your knife to hang lower from the waist, letting it move freely.
The lower position means your knife no longer "catches" when sitting down and is more readily accessible when wearing a jacket. The D-ring also means that you can remove the knife (in it's sheath) without having undo your belt.
The D-ring is made of sturdy 8mm thick aluminum and tested up to a 450kg breaking load which means that you can use it for lots of different purposes, for example to hang up equipment or anchor a dog lead to your waist.
Note that the D-ring should not be used when climbing as falling can create forces that significantly exceed 450kg.
The belt loop is made of sturdy 3mm thick vegetable tanned cowhide available in Cognac Brown or Black. The loop can take belts with a width up to 5cm. The Dangler's D-ring will take knife sheaths with a belt loop up to 34mm wide.