Sizes :
3x3x250mm, outer size 3*3mm, length about 250mm, wall thickness 0.3mm, inner hole 2.4x2.4mm.
4x4x250mm, outer size 4*4mm, length about 250mm, wall thickness 0.4mm, inner hole 3.2x3.2mm.
5x5x250mm, outer size 5*5mm, length about 250mm, wall thickness 0.5mm, inner hole 4x4mm.
6x6x250mm, outer size 6*6mm, length about 250mm, wall thickness 0.6mm, inner hole 4.8x4.8mm.
8x8x250mm, outer size 8*8mm, length about 250mm, wall thickness 0.7mm, inner hole 6.6x6.6mm.
10x10x250mm, outer size 10*10mm, length about 250mm, wall thickness 0.7mm, inner hole 8.6x8.6mm.