Identify these wheel bolt heads / covers

[brotherharry]

So, bought a used project car recently and went to take a bolt off a wheel in order to figure out what type of seating and size specification I'd need to get a set of locking wheel nuts. Discovered that what looks like the bolt head isn't a straight hex shape, but has a bunch of semi-circular channels on it. Hopefully photo / diagram shows what I'm seeing.



I can't tell if it's a bolt cover or the actual bolt. Doesn't feel very plastic-y or loose (I tried gently prying but didn't get anywhere), so thinking these are the actual bolts. Same on every bolt of every wheel. Wheels are after market OZ Supertusimos.

Suggestions or identification please?

[brotherharry]

Cheers, I've just noticed when I zoomed in what looks like logo of the manufacturer tpi, which helped narrow things down further.

Off to the shops for a 6 spline drive adapter key!