I decided to repost this which was originally in the open water thread discussion of the Open Water Safety Device. The post really belongs here in the triathlon thread.
I have the SSD and it isn't bad, but the new Swim It is much less intrusive and it is race legal (USAT and WTC). It is a self-inflating (using a standard co2 cartridge like you use for your bike), reusable life preserver tucked into a small pouch that sits just under your rear, high on the thigh. It is attached to the leg with 2 wide velcro and neoprene straps so it stays on and it is virtually undetectible to the wearer when you have a wetsuit on.
It is not a stash bag so it is not identical to some models of the SSD.
You only deploy it if you need it, rather than the SSD which is inflated and drags behind you all the time. The Swim It is deployed by pulling a plastic tab (you have to pull hard enough that it is unlikely to deploy by accident).
I teach Open Water Courses for Triathletes and this device is wonderful. In fact it is required equipment for the Ocean Skills Course that I teach.
Here is a link to the site...http://myswimit.com
I personally think USAT and WTC should make it required equipment to given the plethora of swim deaths that have occurred in tris...but I digress.