A simple M8x45 Cap Screw Can be used to join Profiles. Form tap one profile with an M8x1.25 thread & counter bore the opposing profile with a 15mm dia. c'bore 15.3mm deep & 9mm thru. This connection is strong & doesn't require the profile to be slid in from the end. The counter bore & screw technique is particularly use full when it is desirable to make an entire wall or side of a construction removable.