Bahtinov Mask That Focusing for Telescope - FM140mm for a Tube Outer Diameter (OD) from 150mm-200mm - can be Mounted with The Brass Screws Inside or Outside The drawtube Black

Due to adjustments I use this on several OTAs and am quite satisfied

I bought 2. One for my 6" and one for my 8". This is specifically about the 6" so I'll only make a passing mention of the 8". That one doesn't make spikes well and what it does make are hard to discern. This one, the 6", is fantastic. Used this the day it arrived. I was imaging Saturn and Jupiter that night. Slewed to a nearby star, focused using the bahtinov mask which was a breeze. Took all of about 5 seconds to focus using this. Slewed back to Saturn and started imaging.

I liked this mask but even under the sun, the heat warps the plastic, should have been made of sturdier stuff.

Breaks easily if not careful. The hardware is too small so I changed to 8-32 screws washers and nuts. This will prevent mask breaking.Clear skies!

I picked this up for my Celestron Nexstar 6se. I could not assemble it. The screws were much too big for the slots they were supposed to slide into. The end result was a busted mask. I would keep away from getting this Bahtinov mask.

Like other reviewers, two of my family could not figure out how the wide posts fit into the narrow slots on the brittle plexiglass mask. The product came direct from Astromania with no instructions for inserting the posts and I see none on the Astromania website. So, first we accidentally broke one of the three legs of the mask in two places trying to insert a post. After I drilled the first hole in the mask to widen the slot, and was inserting the post, it miraculously unscrewed in the middle. I've now mounted the overpriced mask on the objective of my 5" refractor after taking apart all three screws, then positioning the mask on the telescope, and screwing the two ends of the scews together with the mask in a sng position. I did not need any instructions to figure that out!

Excelente calidad del producto. Cortes limpios y perfectos, tamaño exacto. Ligero y buena presentación. Yo pienso que si lo cuido bien podría durarme varios años. Pero está fabricado de policarbonato, no esperes una pieza de metal.

Easy to install , after processing good sighting on my telescope.

Came out of the box broken...~Update-I did get a full refund. Thank you!