The Metal dewcap + Bahtinov mask for ZWO SeeStar S50 smartphone is practically two handy tools in one package. The dewcap protects your instrument from premature fogging, allowing you to spend more time under the sky with your instrument. The Bathinov mask, which can be fitted to the dewcap, is a great help in accurate focusing.
The dewcap is made of black anodised aluminium, with a double o-ring for a stable, drop-proof fit.