I'm with Crossbow on the Broveda pack for testing hygrometers.
Cellophane "on" Cellophane "off". Been an ongoing discussion among Herf for many a moon. MRN's book says it delays aging if you leave them on but the foot is less likely to be knicked by handling.
If you send some sticks out make sure they are all cellophaned-up. Or at least rolled in saran-wrap. If you have a naked stick next to a cellophaned stick the naked one will take a beating in-transient.
Beetle Larvae can eat right through cellophane.
Cellophane wrap is semi-permeable and gas can travel through it. It is not plastic.
My recommendation is if you can store them in your humidifier in-the-original-box; take the cellophane off and close the box.
If you get them from Kevin's you won't have that problem!