In my case I use 18mm outer, 16mm inner diameter pipe. Make sure it's annealed. You might have issues fitting the larger one in this. You kinda want to have the inner diameter of the pipe he squeezed to be as close to the width of the braid as possible. That's why I went with 25mm braid since 16mm*pi/2 = 25mm. The next one up is 35mm, so that would mean an inner diameter around 22mm or so. This does make your contacts quite large. Another thing you can do is double up on the 25mm braid (so make 300A versions). It needs a bit of 'finesse' to find the correct initial amount of squeezing of the pipe to put the double braid in, but it's doable after some practice.