Total Performance. With a price tag, including shipping, of nearly $3000, it is a bit out of my price range now.
Enter the Finis SpeedBox. At a price tag of around $650, including shipping, it is a much more affordable option. Although it is not nearly as sophisticated a device, perhaps it's weight and portability make up for it.
The SpeedBox is a resistance training and sprint assistance training device that is a big step up from Stretchcordz brand bands. The spring, pulley, and bungie system provides a much more even tension over a greater distance than bands. The belt and hook come with a neoprene cover that provide much more comfort for the swimmer. The SpeedBox sits on top of your block and has two anchors to hold it in place.
I did not really have too many criticisms of the SpeedBox save one. It is not easy to get the clasp completely applied. There were several time during our inaugural use of the Speedbox, when the clasp came loose and the belt came off. Every time, this happened during the initial push off.
So far I have used it for sets of quick 10 second sprints as well as 25yd assisted sprints. It has worked well for both. Overall, I would give the Finis SpeedBox two thumbs up. It is hardly a cheap purchase, but it seems sturdy and may be a better long term purchase than bands.