Brass, wonderfully well worn, 1 1/8" diameter circle with pin in center (decorated with sun!) On that side you can quickly find sunrise/Sunset times, how long the day and night lasts, and the months of the year. The other side has days of the week and days of the month. The ends of those days are worn down from repeated pressure/spinning. Someone used this a LOT! c. 1880 or 90, a giveaway promotional item from Perry & Co - their wiki page says "James Perry, still a schoolmaster and being dissatisfied with the quality of existing pens, began making steel pens by hand. The firm was founded in Manchester as James Perry and Co. in 1824, but later moved to London, where they made and sold pens and pen-holders, pencils, elastic bands and ink, and dealt in stationers' supplies."