What type of screw heads are these?

[NHW]

Thinking of replacing the handles on my windows but because theres existing holes in the window I'd rather keep the new handles in the same position. Except I have never seen these types of screws before? Seems like there's just a hole in the middle, tried an Allen key and nothing seems to bite.

Just wondering if anybody had an idea? Thank you

 

[Burnerman]

Those are rivets, I’m afraid......but they can be drilled out!
John

 

[NHW]

Those are rivets, I’m afraid......but they can be drilled out!
John

Ahhhhhh thanks for that info John, I just looked up and realised how it works.

I'm guessing I'm going to have to find window handles that either span across all 4 holes so that it is covered, or try find similar window handles (which I think is called cockspur handles) in order for it to look clean and flush

 

[Harry Bloomfield]

Yep, rivets

 

[Burnerman]

Good luck with your search! Those rivets were set by an industrial riveter, but DIY pop rivets will suffice.
Choose some that will suit the existing hole - usually 5mm diameter.
John

 

[foxhole]

Maybe buy a few to cover future failures.

https://www.amazon.co.uk/Blesiya-Window-Handle-Locking-Replacement/dp/B09HC4KJWQ/ref=asc_df_B09HC4KJWQ/?tag=googshopuk-21&linkCode=df0&hvadid=606569439067&hvpos=&hvnetw=g&hvrand=12487613211362441926&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1006637&hvtargid=pla-1681049008031&psc=1