My Guild M-20 has one that comes with the case. I started to humidify the guitar around this time last year. I also have a Blueridge BR-140 that will need a humidifier. The only other all solid wood would be my Martin D Jr. I have a few solid wood tops with laminate back and sides that I think should be good with just a room humifier. So I'm thinking of only purchasing only 2 soundhole humidifiers. What is your routine this time of year regarding acoustic humidification?