I had a second humidor with a poor humidification system so purchased the Boveda 6 pack of 72%. They work brilliantly and have kept the humidity at an ideal level for a long time. Each sachet is sealed in its own bag so stays as new until you need to use it. Would definitely recommend.
After having issues with my humidity analogue, I turned to these to see what the hype was all about. Happy to say they are literally magic! Would 100% recommend!