I have one for my EL 10X42s. I think they do offer an ultralight alternative to carrying a scope, but are not without their drawbacks. The optics are, of course, very good, so the image is very sharp, but 42mm is a pretty small objective for 20X, so the image is not especially bright. Fine for daylight viewing but they would be tough to digiscope with. Also, 20X is a lot of magnification to hand-hold, so you might want to consider using it together with the Swaro tripod adapter and a light tripod or monopod. If not, you will at least want to lean against a tree or something to help steady them. The field of view is fairly narrow but you can use the other barrel of your bins like a finder scope to get on the bird. All of these issues would be less of a problem if your bins are 8 or 8.5X. They have very long eye relief, much longer (2X as long?) as the bins by themselves. Finally, it takes several seconds to unscrew the eyecup and screw on the doubler so you cannot get on a bird as quickly as if you were carrying a scope in your hand. You can walk around with the doubler already attached and use just the other barrel until you need the extra reach. All in all, I would say they are not a great substitute for a scope, but they are a lot better than bins alone on those occasions when you don't want to carry a scope. Glen