Synrad FH Flyer and Fenix Flyer marking products use extremely expensive lenses which are mounted in a lens mount with an O.D. of 4.1”. Older out of production versions of Synrad marking heads had a lens mount with a 3.25" O.D. The Lens Savers® windows adapter for these lens mounts slips over the outside of the 4.1” or 3.25" cylindrical section of the lens mount that protrudes from the marking head and is affixed to the lens mount with an "O" ring on the internal circumference of the adapter or with bolts for which a bolt circle is also provided that conforms to the bolt circle on the Synrad OEM lens mount. Although Synrad systems do not employ high pressure, the lens mount is designed to equalize the pressure and to maximize air circulation for cooling.