From the Orion web site:
"This versatile filter acts like a dimmer switch for your telescope, toning down the brightness of the Moon or planets to a level that is comfortable. The reduction in brightness and glare unmasks detail in your viewing subject and greatly improves contrast. The filter consists of two high-grade glass polarizing filters in a rotating cell that allows you to adjust the amount of light transmission from 1% to 40%. Such control is highly desirable for lunar observing because the Moon's brightness varies with its phase. The filter is great for terrestrial observing too, especially on sunny days. The filter has an anodized aluminum cell, which threads into the barrel of any standard eyepiece."
Purchased new in January ($36 shipped from Orion), I am upgrading to a 2" version and no longer need this one. You can either use it with an ep, or put one half on you diagonal and the other half on your ep and turn the ep to vary the amount of light reduction. The filter is in like new condition and will ship with original storage case (and original manfacturer's packaging if I can find it). I will sell this one for $27 shipped CONUS. Paypal is my preferred method of payment.