Used Radian Triad Quad-Band Narrowband Filter (2'')This is a 2" Triad Quad Band Filter in excellent condition. It comes in its original jewel box. Any dust you see in the photos is removable it seems that these filters develop an electrostatic charge such that the dust in the air is just attracted to the filter. Description Shoot in any light polluted area H beta, OIII, H alpha, and SII Band Passes Works with any camera including DSLRs Exceptional narrowband & luminance filter If your telescope is f 3