The spring loaded ball bearing will hold the nut in place at any angle while still allowing you to move in the slot. Roll in T nuts can be inserted into standard extrusion from the end or the face of the extrusion.

M8-12 Button Head Cap Screws are great for attaching sheet stock or brackets under .125" (3mm) thick.
M8-16 Button Head Cap Screws are great for attaching .188" to .250" (6.3mm) thick brackets.

$0.70