[b1mcp]

I just measured the tube (it's still on the compressor). It's 170mm. It's not critical so a bit shorter would be fine I think.

It needs to be pretty stout tube and able to take the force being applied obviously. My tube is 3mm wall steel.

One other point to note if you are changing to new springs. Because you are effectively shortening the length of the tool with the tube, then there isn't enough length left to fully uncompress the spring when you remove it from the car.

What I did was uncompress as far as the tool allows, then used another standard externally fitted spring compressor to hold the spring at that point while the internal compressor is removed. Hope that makes sense.