* Prices may differ from that shown
The plossl is the most widely distributed and available type of eyepiece available to the modern astronomer , it can be considered the work horse of the eyepiece world. With a myriad of focal lengths and a simple but effective design, its no wonder the humble plossl has come to dominate over such antiquated designs as the Ramsden and Huygenian.
Skywatchers 20mm super plossl represents a benchmark in quality within the low cost category of eyepiece. Using the more traditional 4 lens design as Skywatcher have here, enables them to keep a minimum of glass between the observer and the object being observed, until you get into the premium eyepiece category and are willing to pay the correspondingly higher prices the less glass used in an optical system the better.
To go on those lenses, Skywatcher use an excellent multi layered coating to get as much light through, in the most uninterrupted manner possible. The edges of said lenses are also blackened to improve contrast and avoid stray light, one can imagine the importance of contrast when observing the large diffused galaxies the 20mm plossl excels in displaying.
Optically the 20mm performs brilliantly (considering its incredibly low £20 price tag). Of course there are slight coma issues (especially on my f5 Dob), but I've used eyepieces at 3 times the price which have demonstrated worse abberations.
Around the lip of the eypiece is a comfortable fold up rubber cup, to keep out local light pollution, I prefer this design to the twist up plastic shield variety but that will come down to personal taste. A textured rubber safety ring encircles the waist of the eyepiece, which may sound inconsequential but becomes very important when handling the eyepiece with cold deadened fingers, anything which affords the observer extra grip has to be a good thing.
Considering how expensive astronomy can be as a hobby its wonderful to find a bit of kit that performs so well while sporting a ridiculously low price tag, every astronomer should have a handful of Skywatcher's super plossls in their inventory.
To summise, you quite literally won't find a cheaper eyepiece, let alone one that performs so well. Uniting three of the most important aspects of optical quality, practical comfort and affordability shows why Skywatcher are king of the low cost eyepiece.