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Its a refractor scope. Skywatcher ST120
I got mine from Germany, and as its in the EU i didnt pay the rediculous legal robbery of UK VAT and Import duty, but you can get them in the US as something similar by the name of Orion.
In fact, you dont even need one as big as this Skywatcher ST 120mm. This one was cheap big time - GBP£250 - but contains NO LD/ED glass for CA correction, hence the cheap price.
If you wanted to go up a notch, and i mean a big notch, look for Orion Telescopes in the US around the 80ED model, or 100ED. You'll be paying twice the price, but the IQ is worth it. Europeans get the Skywatcher, and the equivalent is the SW 80ED / 100ED
At this end of the price range, you'll be getting what they call an ED Air Spaced doublet. That means one of the 2 lens elements will be extremely good quality ED Glass, also known as FPL-53 ( Japanese - O'hara ) but there are variations. Also, the Orion and SW 80ED's aperture are round about F7 or F7.5 for 600mm FL. Dont worry about that too much, because they dont equate to the aperture of DSLR lenses
Much bigger money will be Triplet ED scopes, but these get expensive.
But as long as you are careful and research ( like you would for any other DSLR lens you would buy ) you can get great quality and little weight.
Find me a DSLR lens that can reach 600mm natively ( dont count crop factor - its not an FL multiplier ) at wide apertures of f5 like mine, or f6, f7.. that weigh 8.5 Lbs and under, for that sort of money ? Its impossible