How do I turn this type of lockshield valve?

[SolaceMan]

Unscrewed the cap of the lockshield valve on my radiator, this is what I found underneath:

I haven't been able to find any examples of lockshield valves like this on the internet, and I have no idea how I would go about turning it. Can anyone help?

 

[Ben-gee]

The cap should engage with the splines, put it back on .
If the cap has no female version of the splines, you’ll have to resort to a pair of grips to turn the valve.
This will damage the splines but that won’t matter if you only have a plain cap anyway.