[1.25"] I have used an xcel 3x Barlow for imaging solar system objects and also for visual observing, since about 5 years. Felt the need to try out a focal extender this time. This seems to be widely recommended and hence purchased this. I am quite happy with the results I am getting. The build quality seems to be great for this price point. Very happy with this!

[5.65 x 4.5 x 4"] 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!

[1.25"] 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.

[1.25"] 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.

[5] 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.

[5] I ordered this product to multiply magnifications of my eyepieces. I tested it for planets and double stars at very high magnifications, and really like the product. The green color coating looks great. I think $ is a bargain for a four element 3x barlow. B&H shipped really quickly. Overall, I like the B&H service and price, and I highly recommended this 3x barlow.

[1.25"] If you have a reflector or a refractor with a short focal length (under 1000mm), this is a very useful, high-quality Barlow - especially if you want to image planets with a CCD camera. My results have been great so far - much better than what I was able to do with a 2x. If you have a Schmidt- or Maksutov-Cassegrain, this is going to be overkill. I also wouldn't recommend it if you have a single-speed focuser; you really need to be able to fine-tune things to get this to work.

[9.2 oz / 260 g] A good nebulae filter

[1.29 lb] Excellent field flattener and focal reducer for my Explore Scientific ED152 refractor. A must have for doing astrophotography!

[1.29 lb] 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.