The Saut de bras or Cat leap looks easy but it quite difficult to master.
Warm up prior to doing any parkour, you may want to do a sports related warm up, like doing vaults or jumps that you find easy, after streching of course.
Find two walls where one is lower than the other. They should be about the same distance apart that you can jump. Check that there are no sharp objects on the top of either wall e.g. Broken Glass, Nails because we dont want them in your hands! To make it easier check that the landing wall's surface is grippy. The more practised you get at Cat Leaps the bigger jumps you can do.
Stand on the wall which is lower labelled 1. Swing your arms back just like in a normal two-foot jump. Then through them forward and jump to wall 2.
Your hand should land on top of the wall and your feet about half way down. Depending on how grippy the surface of the wall is you may need to put more weight on your hands than your feet or vice versa.
Here is a good example
While you are in the air tuck your legs up slightly to put them in a good landing position. Your hands should be out stretched during the flight in order to grab the wall. You should aim for your hands and feet to hit the wall at the same time, with your legs together. This makes it look neater and makes it easer to stay on the wall once there.
While in the air you may freak out and be scared of hitting your toes too hard on the wall and try to turn them to the side. If you can help it don’t do it. If you do it correctly your toes will not get injured, and it looks much neater if you land straight. But occasionally when the cat leap is so big you might be going at such a speed that if will hurt your toes! Its your judgement.
You can perform the cat leap running, from another vault or even from a spin. 360 cat leaps are getting quite common!