What's the holder called??

[Kotteluringen]

Need a holder that can take a 4.5 x 4.5 cm regel. Preferably one that can be mounted on the wall and then slide the regel into. Does this exist and if so, what is it called?

 

[fgo]

Joist hanger?
https://www.byggmax.se/spik-och-skruv/byggbeslag/balkskor-och-platband/balksko-invandig-p235171

 

[sinuslinus]

It's called Balksko.

 

[Kotteluringen]

Yes, it is one like that but with a front on