No, the reel on this set is not spring wound. I have a set that I use as test leads for troubleshooting that I keep with my multimeter, and I really like it, once I got it correctly wound.
Through reading a fair amount of reviews about this lead set, the leads are often miswound and if you don't resolve this issue on first use, it often tends to get worse. When I got my set, it was very difficult to unwind as the leads were miswound, so I had to take a few minutes with a coworker to completely unwind the set, then had the coworker maintain tension of the leads as I rewound the lead set. Since then, its worked wonderfully and rewinds easily, but was definitely a bit of a pain when I first got it.
For the price and overall build of the leads, its not a bad product for low voltage / control troubleshooting, etc., but be prepared to unwind the set completely when you get it, likely fight the miswinding the first time, but once you get them correctly wound, it easily unwinds, but it is important that you correctly wind it each time you wind it to ensure that the leads do not become tangled within the reel.
Just my two cents.