O-ring specialists?

[FROGGY]

Not on the ZT but I have an air-con problem on the other motor.
Had it tested with a dye tracer and there is a leak on each pipe to the compressor at the compressor joint end. Tech Mech says I need a new compressor (surprise surprise), me, I think borrocks, it needs new O-rings.
Problem is I don't know what to buy, size or material wise. The snotty German dealership don't want to know unless I hand it over to them, and I would rather have them on hand before I do a stripdown.
I am quite prepared to buy a pack of assorted sizes, but I need to know what type of material and size range for this type of application.

Mick