FITS OD 140MM TO 150MM This full aperture filter has a 127mm/5 clear aperture Type 2+ glass filter element. Its mounted in an aluminum cell with a 152mm/6.00 internal diameter to fit scopes with a maximum diameter of mm (). It fits all versions of the Celestron C5 5 Schmidt-Cassegrain telescope (C5, NexStar 5, NexStar 5i, etc.) and Celestron 4.5 reflectors such as the C4.5. It also fits all versions of the Meade ETX- Maksutov-Cassegrain, as well as the original Astro-Tech AT111EDT apochromatic refractor with a 124mm diameter body (not the current scope version with a 114mm body). You can custom fit it to scopes with an O.D. down to 146mm (5-3/4) by using the extra supplied self-adhesive felt. Always remember to install the solar filter before pointing your telescope at the Sun to avoid instant and irreversible damage to your eyesight.