Desi View&reg; S-20190 Desiccant Pack - 3" x 3.5" for the Ambient Weather F007PF Floating Pool and Spa Thermometer Shows at a glance when desiccant needs replacing. Color changes from blue to pink. Protect electronics, aerospace and industrial products during transit or storage. Blue silica gel turns pink when moisture capacity has been reached. Includes one pack. One side of bag is Tyvek, other side is clear film. Bag Dimensions: 3" x 3.5"; Protects Cu Ft: 0.28