Stick with steel bundy tubing, it has been tested & proved over decades of use to be the best value & easiest to use.
Stainless is very difficult to work with. Bending & flaring are much more difficult than normal bundy tubing, even with professional tools. Also stainless flares don't seal very well, so much so they often need a copper seating washer to make an effective seal.
Many guys don't like the look of the greenish finish commonly seen on modern steel bundy tubing, but it is also available in a bright zinc finish which looks very similar to stainless.
Trust me, after 45+ years in the motor trade, many of those making brake pipes & hoses, keep it simple & stay with steel bundy tube.
Dr Terry
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