SBIG ST-4 Replacement Dessicant Canister

The ST-4 accepts a desiccant "ring" similar to the one used in the old ST-5C. This is a ring shaped canister that will fit the ST-4 head in case of loss or destruction of the old desiccant ring. These will only fit the ST-4 heads that were designed to hold the old style desiccant ring.