Here are the bullet points you requested:

- New improved 18mm diameter lens option.

- Better thermal conductivity will remove the heat from the lens more quicker.

- The aluminum mount protects the lens and makes it easier to hold and clean.

- The ZnSe used to make this product is 500-watt rated. It is the best laser-grade ZnSe manufactured by ll-Vl.

- Each lens is engraved to show the beam direction and focal length.

This 12.7mm lens is suspended stress-free with glue, eliminating crystal stress and the need for an O-ring. However, if the diameter of your unfocused laser beam is 10mm or larger, this lens option will not work. If you are not 100% satisfied, you can return it and get full credit for a standard lens.

Please select the focal length from the following options:

- 38.1mm (1.5")

- 50.8mm (2.0")

- 63.5mm (2.5")

- 101.6mm (4.0")

Here are the product specifications:

- Anti-reflective coated lens for <200W.

- Type: Meniscus Laser Focal Lens

- Material: Znse Laser Grade (made in the USA)

- Coating: 10.6um (AR Both Side)

- Diameter Tolerance: +0/-0.13mm

- Center Thickness Tolerance: ± 0.1mm

- Focal Length Tolerance: < 1%

- Clear Aperture: >= 90% Diameter

- Scratch/Dig: 40-20