Those are definitely cool. I wouldn't mind having a few myself. I wouldn't use them on my mj plants but I would use them on my other house plants. I check my mj like 5-6 times a day at least so I never forget to water them. Under-watering them is never an issue for me. Very cool though. I actually may order some of those for my bonsai trees. They are in tiny pots and dry out really quickly. Very interesting. Take care and be safe.