We have three size of connector, that is 28mm, 34mm, 48mm(od)
And shape of which size is below

01 : Connects one tube to a solid object.
02 : Puts two tubes together into a 90 degree corner piece.
03 : Joins two tubes together at 90 degrees.
06 : Produces a 90 degree corner using three tubes.
07 : Puts three tubes together into a corner assembly.
Each tube is 90 degrees apart from each other.
09, 11 : Joins two tubes together into a swivel tee joint.
13 : Combines three tubes into a cross.
17 : Combines four tubes together.
The middle tube is 90 degrees from all other tubes.
105 : Combines pipes and caster(or leveling foot)
109 : Combines pinnect and caster(or leveling foot)
Set screw and key : Mount with set screw.