They hold in all orientations! Caps 8 made from zinc are screwed into the core bores at the end face. They are particularly resistant to mechanical loading and changes in temperature. They can be unscrewed and screwed back on any number of times.
They must be secured into the core bores of the profiles using countersunk screws 8 SF M7.1x16. No threads need to be tapped to do this.
Note: Caps 8 Zn are available in white aluminium and black (0.0.427.09, 0.0.427.11, 0.0.427.13).