Leaking rad bleed screw, does anyone recognise make or type please

Hi all
Just been doing the pre winter checks and went round bleeding the rads. A couple of the bleed screws in my set up are dodgy, whereby they do up to a certain tightness then slip off loose again, one of which is now dripping when the heating is on.
I haven't removed or checked the valves as I'm wary of making them worse, I was hoping I could just buy some replacements. Unfortunately there's nothing similar on ebay or at the merchants websites. House was built around 2002.
Any help would be much appreciated.
Cheers Chris

 

change the full unit ,standard size ,seal included on most of them

 

As above straight swap, the plastic bit is not needed it is just to direct the stream of water when venting.

http://www.screwfix.com/p/radiator-vent-blanking-plug-chrome-bsp/40972

 

Nice one gordongas and footprints, exactly what I want. I scoured screwfix but never saw these.
Much appreciated
Chris

 

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Please select a service and enter a location to continue...

Plumber / Gas Engineer Electrician Builder Decorator Builders' Merchant Plumbers' Merchant Tile Supplier Flooring Supplier
Start Search

Are you a trade or supplier? You can create your listing free at DIYnot Local