I have 2 of these in a 5 cubic feet ported box with 60 sq in of port area, tuned to 50 Hz. This is a good setup for these subs, though a smaller volume will do just fine, down to 3 cf.
The woofers are larger and heavier than the pictures imply. Especially for only an 85oz magnet.
Also, the excursion is quite small (0.7") for an SPL sub. This produces a stronger, punchier bass, but won't get the best dBs, unless you give them plenty of power and an optimally designed box (see above).
There has a definite power range, 200w to 700w RMS of "clean power" (each). At and above the 200w RMS range, they really wang. With proper power, they perform equally to most 12's, but don't expect too much clarity at low listening volumes.
Build quality is excellent, though the terminals could be larger and the paint on the front ring scrapes off easily.
Otherwise, excellent sub and an incredible value. Compares to most entry-level SPL subs, like Orion HCCAs, Audioque SD2.5's, even though they have 1/2 the magnet size, the suspension and cone design make up for it.