First Contact Polymer Toggle Search Account Checkout Cart Home Store: Order Now Kits with FLAT RATE SHIPPING WHO Hand Sanitizer NV Formula Sanitizers NVG Formula Sanitizers NVX Formula Sanitizers All-Inclusive Kits-One Click Plastics Formula Polymer Kits Spray First Contact Bulk Bottles Brushes Accessories, Spray Heads, Kits, and Bottles Orings Thinner Specialty Items Copper, Brass, Nickel & Aluminum Polymer Instructions & Videos Applications Astronomers High Powered Laser Optics LIGO Telescopes: Refractors, SCT, Dobs, etc. Cassegrain Telescopes (SCT, Mak-Cass, etc.) - Material Requirements Reflecting Telescopes (excepts SCTs) - Material Requirements Refracting Telescopes - Material Requirements Phase Masks/Gratings Forensic Fingerprinting Large Observatories FAQ SDS & Tech Data Distributors / Resellers Middle East Asia Africa Americas Europe Contact Visit Us at these Trade Shows! Testimonials & News Press/News/TV Stories FC NV Hand Sanitizer Featured Astrophotography Article by Alex McConahay Click here for Featured Article Archives Search site Submit search Nav Menu 2 Nav Menu 3 Nav Menu 4 Nav Menu 5 Nav Menu 6 Nav Menu 7 Nav Menu 8 Orings - Custom Size 10 to 20 Inch (254.0 to 508.0mm) OD (Sold Individually) Alternative Views: Our Price: $9.00 Product Code: ORING10-20 Custom Size In 1/16th" or 1/10th mm Increments Enter Custom Size*: Enter Your Equipment Details Below Equipment Info: (Mfgr, Model, etc.)*: Qty: Description We will manufacture a custom oring to fit your specific optic. Measure the diameter of your optic just inside the retaining ring (or housing if retained from the back side) and provide the measurement to the next smallest 1/8h inch or 1/10th millimeter measurement. Example: An optic is 8 and 5/8th inch (219.1mm) diameter measured just inside the retaining ring. Enter 8 and 1/2th (or 215.9mm) diameter in the text box. Please provide the name and model number of the equipment so we can retain this information for your next order.These are chemical resistant orings that do not swell when in contact with the polymer. Do not use cheap Butyl or Buna orings, they will absorb solvents, swell and can break down leaving residue. Read our online Oring document with photos and text to explain oring use.NOTES: 1. If the orings are not flat when received and do not lay flat on your optic you can lay on a flat surface and apply mild heat with a heat gun and the orings will flatten. Allow to cool then apply to your optic! 2. The oring may trap a very thin layer of polymer underneath and leave polymer residue when peeled. This possible situation can be avoided by coating one side of the oring with polymer (or dipping), and once dry you can set in place and use per directions.