This does what it says on the tin and fits very snugly into female XLR chassis connectors.
The extra price compared to Neutrik's standalone rubber plugs is worth it because the string means you won't lose the plug every time you take it out.
The angled metal ring is a nice touch as it can then be screwed flush against the plate. We're going to be adding these to all our female XLR and AES connectors, both of which are potential dust traps.