• Product Name: DayStar Imaging FlatCap.
• Function: Serves as a Gaussian diffuser for taking flat field reference images with telescopes.
• Key Feature: Temporarily mounts over the telescope's front end, effectively blurring the Sun to highlight defects in the imaging train for software correction.
• Construction: Made with a spun aluminum mounting ring and a polymer diffuser.
• Intensity Distribution: Gaussian.
• Divergence Angle: 4 degrees Full Width at Half Maximum (FWHM).
• Exposure Time Adjustment: Requires exposure times to be 100x longer.
• Maximum Field of View: Up to 1 degree with Sun backlighting.
• Wavelength Transmission Range: 350-800nm.
• Operating Temperature Range: -10 to 100°C (14-212°F).
• Sizing Guide: Sold by the inside diameter of the mounting cap. Users should measure the outside diameter of their telescope's frontmost component or ERF, then round up to the next larger size (e.g., a 160mm front should use model FC170, with optional felt pads for a secure fit).
• Safety Warning: Not a solar filter. Must not be used in concentrated beams and should be the first component to encounter light to avoid eye or equipment damage. Must be used with a safe solar filter or solar telescope.
• Manufacturing: Proudly made in the USA.

This detailed description emphasizes the FlatCap's specific use, features, and safety instructions, making it helpful for potential buyers and enthusiasts in the field of astronomy and astrophotography.