These knobs make it easy to collimate your older three-screw secondary Meade 16" LX200 Schmidt-Cassegrain for optimum image quality. Current 16" Meade SCTs have six screws in their secondary mirror holder and need Bob's Knobs set #BKM16S. You don't need any tools, so you never have to worry about losing a tiny Allen wrench or screwdriver in the grass in the dark. While it may be a long reach for some people (unless you're a basketball player), you may still adjust the collimation yourself while looking through the eyepiece, so there's instant feedback about how your optics are performing. Installation of the knobs is a snap with the included instructions, and you can undo the modification at any time. This knob set works only with older 16" Meade LX200 Schmidt-Cassegrain telescopes have a three-screw secondary mirror holder. Recent Meade 16" Schmidt-Cassegrains and LX200R Advanced Ritchey-Chrétien telescopes have six screws in their secondary mirror housing, as shown in the feature image below. These scopes require Bob's Knobs set #BKM16S instead of this set. Do not use this set of knobs for the three-screw secondary on the current six-screw secondary. The screws of the three-screw knob set are too long to work with current scopes. The Bob's Knobs collimating screws themselves are made of stainless steel. Their knobs are also stainless steel, 19 mm (3/4") in diameter. The factory dust cover will fit on the scope normally with the collimation knobs installed. The three collimation screws hold the secondary mirror and its mounting plate to the secondary housing. The mirror mounting plate pivots on a tang or spring at its center, and the collimation screws, which are threaded into the plate, adjust the mirror tilt (or collimation). Do not remove more than one of the original collimation screws at a time when installing Bob's Knobs, as the secondary mirror might fall off (if all three screws are removed at the same time), or the secondary can pivot inside the tube, scratching the corrector plate (if two screws are removed simultaneously). By removing only one factory collimation screw at a time, replacing it with a knob, and repeating this process for the other two collimation screws, there's no danger of dropping the secondary mirror. The instructions also recommend pointing the optical tube assembly slightly downward during the installation of the knobs for an added safety measure. Tech Details: Weight 1.6 oz Warranty No Warranty
