Televue have been a company synonymous with quality for a number of years, they are arguably one of the finest producers of astronomical equipment on the market today. There's a good reason for this, the owner of Televue, Al Nagler is an enthusiastic astronomer himself and pours his efforts into making a superior product.
A Barlow, for those who don't know, is a lens that an eyepiece is slotted into then attached to the telescope. The Barlow magnifies any eyepiece inserted into it by a certain factor. This can be useful for a number of reasons. First and foremost it can effectively double your eyepiece collection at a relatively low cost. Secondly it allows you to keep a decent eye relief while observing under higher magnification (eye relief being the maximum distance you can hold your head from the eyepiece lens). A long eye relief means you don't have to keep your eye pressed against the glass of the lens to see the entire field. Thirdly and by no means least importantly, the Barlow is an indispensable tool for the astrophotographer providing much needed magnification which is especially useful on the moon and planets where a good image scale is required.
Aesthetically Televue's Barlow is quite stylish, it's done out in the traditional Televue black and green. Eyepieces are attached via a single silver thumb screw. The Barlow is 5 inches long and quite light, it doesn't cause any balancing issues when I add/remove it from use.
What makes Televue's Barlow better than a lot of the competition is that it only uses two lens elements in it's design as opposed to the more common three lens setup. When you consider that the addition of a Barlow is adding extra glass between you and the object you're observing (which can only stand to degrade image quality) the fact that there's one less element than you'd expect is very welcome indeed. This makes the Televue a little sharper than some other Barlows I've looked through and there is a significant reduction in light scatter.
At £80 it's not the lowest priced Barlow available but with so many dodgy cheap Barlows out there which degrade image quality to an unusable extent it is well worth splashing out that bit extra to ensure you're getting a decent lens.
A definite recommendation for it's optical quality as well as it's light but robust build.