The butyl isn't the lightest but it's pretty sturdy for daily use and I don't have to fuss with valve extenders on my carbon wheels. I like that they are pretty durable and have smooth valve stems so my pump doesn't get chewed up. They hold air well and last quite a long time for me.
I only use smooth stem tubes on my bikes as they do not tear up the o-ring seal on my pump. Smooth stems are hard to find as most manufacturers insist on putting the unneeded threads on their tubes. However they are available here at a decent price. These are good quality tubes too. I have been using them for many years and have never had a flat as a result of a fault of the tube.
Michelin tubes seem to have a better quality stem than other brands. The presta valve just seems to have a more substantial feel to it than others. The tubes hold full pressure longer than others, not necessary to check pressure before every ride. Not sure if it is the quality of the rubber or just better construction. Before getting these tubes, I thought a tube is a tube, they all hold air, but apparently some do it better than others!
There's nothing I don't like about A1 Airstops. They have the right balance of lightness and puncture resistance. The valves are smooth so they don't chew up the chuck on my air pump. The 40mm stem length is perfect for HED Ardennes and other low-profile wheels.
I'm lazy and don't like to pump up tires before every ride. Michelin Airstops loose pressure at a very low rate, so I inflate on Friday and ride all weekend secure in the knowledge that my tires are still in the set pressure range. I also love the smooth valve stems as they don't chew up the rubber seal on my track pump.
Good tube for 25 mm wide tires. I prefer the quality of Michelin tubes over others, less seam splitting and the slightly extra rubber helps resist those tiny pin pricks that can damage ultra light tubes. Probably want something lighter to stay competitive for racing. But if you don't like sitting on the side of the road fixing flats during training or recreational rides give these a try. I use tires weighing 215 to 240 gms on my road bike on city and country roads.
Even though the description does not say anything about the valve core, I bought these because someone complained that the cores came out when they used screw-on pumps. Unfortunately that information was incorrect. These do not have removable valve cores.