There are lots of problems
with normal weight systems.
They can be dumped, by accident or folly. The fact is you should never
need to dump weights because as you start to rise, all residual air expands
in your dry suit or your wet suit decompresses, causing you to rise faster.
I cannot find a single accident report from a properly weighted diver not
being able to dump weight, but I see plenty from weights being dumped accidentally.
The weights are around your waist, and tend to slip as the suit fills
The buckle interferes with mounting your BCD buckle where it belongs
(on your hip).
The weights on you, with wing behind, push you face into the water.
It can be very hard getting on your back to swim if you use a technical
The keel weights overcome all these problems.
The mount via the cam bands or cylinder bands on your tanks. This pushes
you onto your back into a mouth-out-of-water position on the surface.
The weights cannot be released and do not slip. A pair is designed
to hold 23lb, but can hold almost 40lb. I use one on each tank to avoid
tilting on one side. By the way, if you use more than 23lb in total you
are probably overweighted: I can get down fine using 23lb with a dry suit,
or a 8mm wet suit, with a single tank and no backplate or ankle weights.
With twin tanks, I can get down with 16lb in the same rigs.
There is no buckle, so your BCD buckle can now be where it need to
be, on your hip like a mountaineering rucksack.
By the way, the keel weight tube also acts as a battery compartment
for a Dive Light: it is important to fit the O ring as indicated.
The end-cap screws on using an Allen key in the hole.
a single cylinder on a technical harness using cam bands, or reversing
the plate, the twinning bands attach to the plate, and the plate attaches
to the wing and harness through the standard bolt holes in the wing. This
is necessary if you want to strap the tanks lower than normal: a good idea
because some harnesses have a cam band almost around the neck of a cylinder
at the right height.
Another reason for mounting cylinders lower is if you have a manifold
protector, to save the protector from wacking your head as you look up.