Bob's Knobs Meade 16” SCT Secondary Knobs: Perfect Collimation for 6-Screw Versions Effortless Collimation: Achieve precise collimation adjustments with ease for Meade 16” SCT telescopes equipped with a 6-Screw secondary housing. Bob's Knobs ensures a hassle-free experience. Part Details - Part: M16-6: Custom-Made for 6-Screw Models: These stainless steel knobs are exclusively designed for Meade 16” f/10 SCT versions featuring six screws on the secondary housing. Comfortable Diameter: With a generous 19 mm (3/4”) diameter, these knobs offer ease of handling and accurate adjustments. Durable Threads: Crafted with stainless steel threads, these knobs guarantee durability and reliability. Factory Dust Cover Fit: The factory dust cover will seamlessly fit with Bob's Knobs installed. Compatibility Reminder: Earlier Meade 16” telescopes may have three screws on the secondary housing. For these scopes, refer to Item A (above). Do not use 6-screw knobs on the 3-screw secondary, as the screws on the 6-screw knobs are longer. Included Allen Wrench: Your order includes a convenient Allen wrench for the removal of factory collimation screws during installation. Knob Selection: Carefully select the appropriate knobs for your telescope, as each knob set is unique and not interchangeable. The price includes a complete set of knobs.