Michelin A3 ProTek Max 700x32-42 Self-Sealing Tube Presta. Thanks to its uneven design, the MICHELIN Protek Max has a "compression" reaction in the event of piercing or nipping (the hole closes up naturally) whereas a classic inner tube has an "extension"
Strengths: Doesn't lump like other sealant tubes
very resilient against punctures
Weaknesses: A little heavy
Large uninflated makes installation a little tricky
Other than the slight downfalls of the resigned shape (weight and fitting), it has worked very well for me. I do a lot of riding around the city as well as off road for fun. The area I live in is very woodsy and has thorns everywhere. I would go through a new pair of tubes at least 3 times a month because of punctures from both, glass, thorns, metal shards, etc. I tried these tubes out on a whim hoping they'd be worth their high price. This was 16 months ago. I still haven't needed to replace my tubes. Out of curiosity I deflated and removed one and once it was no longer compressed inside of the tire the punctures and tears became visible. I counted 16 punctures and 3 tears in the tube once it was deflated. I put it back in the tire and pumped it up and the compression idea truly works. It holds air even though it's full of holes. I was very surprised.