Don't really know them other than that they are one of Celestion's cheaper speakers.
This from the guy who designed them for Celestion:
Super 65 is a new speaker designed to meet a price target rather than a performance one. It's by no means a bad speaker, but has little in common with the old G12-65. The construction is different, the magnet is smaller and the tone is less sweet and less clear. They are probably better suited to high gain solid state than valve.
They have a 1.75" dia coil on Kapton, a 25oz ceramic magnet and a sensitivity of about 96dB (1W@1m). The bass is a fair compromise of warmth and definition, a bit boomy but not bad, the mid is a little hald back due to the smaller magnet and the treble a bit fuzzy due to the modern build and materials. It's a good speaker for the money, and one I am quite proud of, but given a free hand I'd have put a bigger magnet on it and spent a bit longer fine tuning the cone spec to sweeten the treble a bit more.