"Great product! I really recommend this for new and experienced fermenters alike. I am relatively new to making sauerkrauts and so I was worried about not making it right. I ended up reading about the importance of keeping the cabbage in an anaerobic environment, which led me to these lids. There are a few other air lock products out there but I like that I can use the pump to remove air after I've open the lids. I've had to add additional brine to my first batch of sauerkraut after some overflowed and so I'm glad I was able to use the air pump."