[478 to 496 nm] I paid Only 99 dollars to get this FExtender w/4 optical elements, cause it was on discount!. Thanks B&H for that! Quality is superb and after a few weeks I am pleased with buying. I have improved my observation and photo/video capacity of my Comet Hunter. Great job of Exp. Scientific with this 2X extender. Highly recomendable.

[0.55 lb] The filter came boxed extremely well. I knew, right off the bat, the product was going to be great. Living in Eastern Idaho, one cannot be sure of the weather and cloud cover. I only had one chance to use it during our club's 5 star parties. 4 got rained out or cloud covered. The filter never got a good critique. I know it will be good and will send in a later review if I can get the scope to a dark site before the temp drops into the teens.

[94.5%] There are many A+ reviews about the 2x Extender from Explore Scientific! Add my opinion as A+. Okay, so the glass is excellent and the machining of the unit is exemplary - fit & finish unbeatable. What puts this above & beyond are the instructions are easy to read & understand, and the box from ES is an amazing work of art and utility! Seriously! The box alone is probably worth keeping & displaying at any gathering! The extender is hefty and is packed well within; a given. The covering is based on Wil Tirion's Uranography & Graphic Design! My wife was more impressed with the boxes, than the gadgets! Guys, ponder it. I may survive this purchase. LOL!

[94.5%] I have had nothing but cloudy weather every since I purchased it.
Tonight however I had a very short window to give it a try. I used it in conjunction with an Explore Scientific 14mm 82 degree field eyepiece as a test. Viewing Jupiter through my 6 inch Celestron Evolution telescope the 14mm gives me 107x. The view was very sharp. When
I added the 2x focal extender the view of Jupiter lost no sharpness or contrast. Magnification was now 214x on a very average night. This is the best by far of a variety of 2x Barlows that I have used over quite a long period of observing.

[Glass] I've only run one night with this but from what I can see, there was no degradation of visual or photographic by putting this into the optical path, the build is rock solid.

[94.5%] I use the 2 2X Explore Scientific Focal Extender with 2 Eyepieces in 25, 30, 35mm (70 degree FOV Bressers) primarily for viewing Deep Sky Objects: Clusters, Nebulas and Galaxies. My scope is a Meade LX 90 8 inch. The results with the 2 extender are pretty amazing. I begin by using a 20 or 25 mm eyepiece without the extender to find the object. Then for the increased magnification I switch to the 2 extender with either the 25 mm or 30 mm 2 eyepiece . Before getting the 2 extender I used a 1.25 2X extender (also Explore Scientific) with Plossls for viewing the deep sky objects. For the most part, with that setup the objects were bright and clear but, with the narrow FOV of the Plossls, not as dramatic. With the 2 extender and the 2 Bressers the clusters and nebulas are bigger, brighter, well defined objects. The clusters especially are bright and clear with many well defined points of light. The Galaxies are still fuzzy objects, but magnified. If there is a downside to the use of the 2 extender for me, it might be the weight. The combination of the 2 Extender, a 2 Diagonal, and a 2 eyepiece is heavy. But, so far, the scope performs just as it did with the 1.25 setup. Also, the 2 setup prevents the scope from going to zeinth. A 1.25 adapter is included with the extender so it is not necessary to have both the 1.25 and the 2 extenders. I am completely satisfied with the extender.

[Glass] Used this filter with Explore Scientific ED127 triplet and got good results, My photographs are better with filter also own the UHC filter from explore scientific and it is also good

[94.5%] A good nebulae filter