These wheels contain a set of neutral-density (ND) ﬁlters mounted in a single easy-to-use unit. The simple two-wheel design of the Model 5215 gives you a wide range of optical densities, from 0.08 to 3.0 in 0.1 increments. The Model 5214 is a single-wheel version.Each wheel includes six 1"-diameter ﬁlters. The ﬁlter positions are mechanically indexed for precise positioning and the ﬁlters are made with Inconel metallic coatings on glass substrates. We mount the ﬁlters at a slight angle to reduce étalon effects, although there will be some residual étalon effects for beam diameters greater than a few millimeters.These ﬁlter wheels are less expensive than circular variable attenuators and offer greater precision. Since each wheel contains discrete ﬁlters, you know the exact optical density and can accurately measure laser powers over a large dynamic range. Unlike other neutral-density ﬁlter sets, our ﬁlters are all in a single handy mount. You wont have to deal with clunky ﬁlter holders, missing ﬁlters, or (someone elses) ﬁngerprints any more.All our ND-ﬁlter wheels have an 8-32 (M4) clearance hole so they can mount directly to a post or pedestal riser.