I swear by the tempo trainer especially because I swim without a coach. Its great for focising in on my stroke rate and mode 2 is great for speed work.

Helped with my first half I'M swim

The swim team coach had my daughter put this INSIDE HER SWIM CAP instead of on the strap of her goggles, and she said it was incredibly loud!  The difference between this model and the next one up is that the other one floats, this one doesn't.  It's not a big deal, though... the blue one works just fine!

Just learned how to swim about 2.5 years ago. And now I've been trying to improve my tempo/efficiency so my TI instructor suggested this trainer.  I have been using it over a year now and it still going strong. Very simple to use...

I had terrible luck with half a dozen of these.  One worked great and lasted over a year.  The others died after a few months (50 hours of workouts) or the buttons never worked properly to begin with.  Have had excellent results with the new Tempo Trainer Pro version, see my review there.

Great item. Perfect training companion. Used it for both swimming and Chi-running (cadence) for 4 months prior to NYC Marathon, then it died 2weeks prior to race day. Only used it 8-10 hours per week for ~16 weeks. By the random online posts... it appears some folks claim they get 2.5 years out of battery. I'm guessing that's light use. And yes... Unfortunately it seems there's no way to replace the battery. So, I chalk it up to $30 bucks invested in a race training... similar to a pair of shoes, socks or whatever. Aside from short life... very good product if you know how to use it (Total Immersion/Chi Running).