all pros, no real cons, except for those occasional times you need to chase down a ball that went rolling across the floor for one reason or another lol.been using these balls several times a week for nearly two months with a small lid-less cooler for my sous vide cooks. they work great instead of drilling a hole in the lid - even better, I have read that using a lid can force steam to escape around the opening for the sous vide unit, forcing condensation up into the unit which will eventually damage it, but that doesn't appear to be a potential problem when using these balls. I'd considered buying cheaper ping pong balls (not tournament or regular play quality but the really cheap ones that don't bounce well) but they are so large you couldn't really layer them, and it makes more sense to use several layers of smaller balls to better trap heat and steam from escaping.one bag works well for my small cooler opening which is about 8" x 10.5" so that there are two layers of balls to trap heat from escaping. I have noticed some heat/steam escape at higher temp cooks like 183F when I do carrots, and I do believe another layer of balls would fix it, but this is like a 2 hour cook so no real need to worry about much evaporation with that. I've never had an issue with heat escaping with lower temp cooks like 137F for ribeyes and lower for leaner cuts of meat. I've also done several 24 and 36 hour cooks for tougher cuts of meat (131-137F) without a noticeable reduction in water level by the end.regarding the bag not drying as other reviews have mentioned, I've personally had no issues with the bag drying quickly. maybe they changed the bag that is included, but I doubt it. not sure what these ppl are doing, maybe putting them up wet in a cabinet? I pull the balls out of the water and drop directly in the bag, wet as they are and water dripping off my hands, then set it on my dish drying rack where there's no real sun or air circulation in that area, but no problems. everything dries quickly. hour or two probably I don't really check or time it, but the point is they dry just fine.