Cablemount for wall and ceiling screwable

I designed this cable holder for walls and ceilings because I needed a single such holder and I could only buy several of them for a few euros. So I just made this myself. Have used the holder for a ceiling lamp with pendant light.
The holder is designed for cables with up to 7mm diameter. For mounting there is a 4mm hole for countersunk screws.

Because I am new in the field, please let me your opinion there, criticism is welcome.