Check the listing for details. Replacement Telescope focus knob Universal 6mm tuner slot. 20mm outer diameter. Color: black, Condition: New. Listed at 8.99 USD. Fine Focus Knob upgrade or replacement knob. Fits any 6mm bar or slotted tuner bar that is under original knob. Knob should have a flat surface and this knob has a set in nut with bolt that tightens down onto that 6mm focus bar. I also make 4mm ,6mm, 8mm, or any other size just let me know the bar diameter. Has set in nut with bolt for tight and secure tuning. Condition is "New". Shipped with USPS First Class Mail. Made and designed from 3D printing software, fitted and tested. Made from Spencer-3D, made in United States. Comes in Black as is but can have in other colors when requested. Just message if need a different color or need a custom part. This knob is 20mm diameter and is perfect for fine tuning its sometimes hard to do with a small knob. Faster tuning when it counts. 2 to 3 day U.S. shipping. LEAVE NOTE ON PURCHASE WITH COLOR YOU WANT, OR ELSE IT WILL COME IN BLACK. THEY CAN BE MADE IN ANY COLOR JUST ABOUT, AND ALSO GLOW IN DARK BLUE, OR GLOW IN DARK GREEN.