Thanks. Is one safer than the other i.e. internal Vs external? And is there a max length? Could I do 3 x 2 meter with 2 joining pieces or even 4 X 2 meter with 3 joining pieces?
Dunno, if I'm honest. You might be best off asking Kee Systems that question. It's pretty robust stuff. My desk is supported by it. I can confirm that it'll support the weight of two consenting adults shagging on it.
Kee Systems will do something that will do that job.
They have two different types - internal and external.