Review on Astromania Flexible Dew Shield For Telescope Front Outer Diameter From 100-123Mm Diameter - Keep Dew Away And Gives You Clear Observing For The Entire Night by Rob Allen

I ordered the shield for a 123mm to 142mm diameter scope for my NexStar 127 SLT going by the aperture of 127mm. Wrong! It was too small. The outside diameter of the scope is 144mm. I ordered the 147mm to 167mm and it fits perfectly. In retrospect, if I had read the description more carefully, I would have seen that the dew shields are sized for the front Outside Diameter of the scope. This is a great dew shield. It fits well, stays in place, blocks extraneous light and prevented the formation of dew on the front plate of my scope when I was using it tonight.