Worker very very well for my nighttime heavy wetter.
I bought two of these inserts, a medium overnight bamboo and a large overnight hemp, and after washing they are the same size (about 12.75".) So just be aware that the overnight hemp will probably shrink a ton, so you may want to buy one size up in the overnight hemp. Doesn't affect it's performance for me, I was just surprised at how much it shrank. I also personally think that the overnight bamboo is more absorbent than the overnight hemp.
I have now tried all three inserts - the microfiber stay drys, hemp, and bamboo. The winner is the microfiber. My son is a heavy wetter and MF seems to hold the most waste, prevent leaks the best, and keeps his little bottom moisture free. At a diaper change (about every 3 hours) I can touch his little bottom and not feel any wetness on his skin. For us, hemp came in second. Super trim & absorbent... just not of the same caliber as the MF. I would recommend getting some for those baby jeans or outfits that need a trimmer diaper. Bamboo just didn't stand up to the other two for us. They are very trim & very soft, but it seems like his bottom has more moisture on it and there were more frequent leaks. I also tried out the overnight MF inserts with regular MF insert on top. I wish I would have gotten hemp for the overnight insert because MF on top of MF is very very thick. Overall, the overnight inserts are totally worth it because it is so nice to not have to change the diaper overnight! My son seems to sleep better & longer.
Love the Best Bottom diaper system! We've been using it for nearly a month now and both the husband and I agree it is easy and efficient. I ordered both the bamboo and microfiber inserts in size small for our newborn boy. I have found that I prefer the microfiber inserts as they seem to absorb more and keep the wetness off his skin. The bamboo inserts have their place, though, as they certainly are much trimmer than the microfiber and work better with certain outfits. Overall we are very happy with this system.
I'm super pleased with these inserts. I own both the stay dry and the bamboo. I cannot believe how trim the new bamboo options are and their absorbency is also absolutely fabulous. We've been able to use them both overnight and for day use without any problems. They also clean like a dream! Lots of super disgusting older child "ick" and not a single stain! Unbelievable!