Focal length: 12.5mm
Barrel size: 1.25-inch
Design: 4 element plossl (2)(2) configuration
Optics: multi-coated
Field of view: 51 degrees
Eye relief: 6mm
Exit aperture: 11.3mm
Threaded for filters: yes
Materials: milled aluminum and bronze, glass
Weight: 3.1 ounces
These eyepieces are each outstanding performers for the price and I would directly equal them to the Orion Sirius Plossls of post-2015; the years from China at which they were reinstated with multi-coated optics. I have tested them to be far better than any of the Meade Modified Achromats made after their Series II (pre-1986), they are equal to the very early years Orion Explorer IIs and Celestron SMAs (though these kellner hybrids have less eye relief), and they are better in build quality than most of your standard eyepiece kit plossls that come in the shiny aluminum cases (very popular from 2015-2020).
The 20mm and 15mm have long enough eye relief that some eyeglass wearers will be able to get along with them while keeping their lenses on. The 12.5mm's eye relief is too close and will not work for those of you who absolutely must keep eyeglasses on during observing activities. For those who do not require spectacles at the eyepiece, these plossls will be very comfortable to use, and for those with a younger audience, positioning with these eyepieces is super easy and straight forward.
Each of these (3) oculars will provide excellent color correction and when used in apochromat refractors, reflectors of f/5 or slower and cassegrains of f/7 or faster, there will be no false color fringing issues. The multi-coatings on them are definitely an improvement over fully coated plossls as you will get far less ghosting (irradiation and extraneous glow), but these plossls' multi-coatings are NOT as good as what you will find on Japanese plossls from the 1990s.
The 20mm will be perfect for getting up close to open clusters and larger galaxies and diffuse nebulae without "boxing-in" the view too tightly. Try this on M52, M11, M17, M33, M31, M51, and M37. It can also be a marvelous eyepiece for the Moon with a neutral density filter when it is at 75% to 100% phase.
And this is a VERY good plossl for use in your daytime terrestrial observing pursuits. Use it in your Orion Apex 102, Meade 2045, Meade ETX90, or Explorer Scientific ED80.
The 15mm is apt for your upper magnification on all things globular clusters, compact open clusters, and planetary nebulae. It will also be about your max power to use on most galaxies. I will often use the 15mm for close observation of Jupiter, Saturn, and Venus when the sky conditions are just so-so, but I still want them to be close enough to bring a "wow" factor to the newcomer.
I've had excellent views with this 15mm in my Edmund Scientific Astroscan, Tele Vue Ranger, Orion SkyView Deluxe 90mm, and Parks Jovian 90 on M94, M51, M42, M13, M92, M3, and M57.
Like the 20mm, this 15mm will work VERY well for daytime observing; though this would be considered a high power ocular in most instances since the atmosphere is going to be unsteady and have wavy turbulence from high noon till sunset.
The 12.5mm will be your go-to plossl for maximum high power views of high surface brightness galaxies when the nights are of very good seeing (stars like Arcturus, Sirius, Capella, and Vega don't twinkle). It is a marvelous eyepiece for lower high power views of the Moon (particularly on the terminator at half phase), and it will do great justice as a high power globular cluster resolver. M13, M92, M22, M15, and M3 will be fun with this eyepiece. Also try it on compact open clusters, like M52, M11, M37, M35, and the Double Cluster.
It will be too high a power for daytime observing in most situations unless you are observing close by. Objects several miles away and angled near the horizon will not look good because the atmosphere is very turbulent at ground level.
I've had only very pleasing results in my Orion Apex 102, Meade ETX90, Orion ShortTube 80, and I seem to enjoy it often in the old Meade 2080.
Each of these plossls cooperate very well with your standard 2x barlows; giving sharp views with excellent color control and not creating out-of-control eye relief. Like I said, for the price and for what they are, these would make a wonderful outreach ocular set in that you will offer the public probably the best views of the heavens they have ever seen before, yet without risking your wallet as part of the process.