Stage 3 & 4-Double Desiccant Air DryerThey are metal bowl filled with desiccant beads which will absorb the last of the moisture and impurities in the air. When the desiccant beads in the metal bowl turn from blue to pink, this indicates that the desiccant beads need to be replaced.
Package Included1* Four Stage Air Drying System, 1* Dial Gauge for the 1/4", 1* Nickel-plated Iron Air Plug, 1* Nickel-plated Iron Air Coupler, 2* 1/2" × 1/2" Male Pipe, 2* 5 Micron Element & 0.01 Micron Element (One of Them is Installed in the Product), 8* Desiccant Beads Bag, 1* Teflon tape.