Tiffen 58mm Sky 1-A Camera Lens Screw-In Filter Black Metal Plastic Case USA

This is a 58mm Sky 1-A camera lens made by Tiffen.

It has a black metal outer ring with a glass lens in the middle. On the side it says "Tiffen 58mm SKY 1-A Made in USA". It come with a plastic case made by Tiffen. 

The lens measures almost 2.5" round and 0.25" thick. the case measures 3" round and 0.75" thick.

 This item comes in good pre-owned condition. There is some writing in black ink on the front of the plastic case.