Hi,
I've not used the Avia but according to
this document (not a clue where i got it from but bloody useful) the stats are:
Avia G-Force Skinny SUL / Skyshark 3PT
Weight: 11g / 12g
Length: 32.5in (82.6cm) / 32.5in (82.6cm)
Deflection: 0.570in (1,4cm) / 0.498in (1.3cm)
Large I.D: 0.2450 (6mm) / 0.2440 (6mm)
Large O.D: 0.2950in (7mm) / 0.2900in (7mm)
Small O.D: 0.158in (4mm) / 0.220in (6mm)
The internal diameter on both is 6mm. Only real difference is the gram of weight and the differing small O.D. as far as i see.