In 12 weeks I’ve had two TT Pros fail & one of the clips break. Shameful quality from the once reliable Finis!
After using the old TT (blue) for a couple of years I thought I’d spring for the new Pro model (yellow) with the strokes per minute mode.
The bracket/clip/holder for the first TT pro showed stress cracks within the first week (I took photos as the it was obvious the cracks would propagate and it would fracture in the near future) and after a few more weeks indeed the clip broke. I contacted Finis to point out the design fault and they eventually shipped me a new clip.
By the time the new clip arrived however the actual timer unit has ceased to function. Tried new battery. Nothing.
To keep training on schedule I ordered another immediately. (Sometimes you get a lemon right?)
The new TT pro lasted 2 swim sessions (3 days) before failing to work properly. It would beep only intermittently, switch itself off during a swim, when trying to adjust the tempo it would switch off, if set to more than 61 strokes per minute it locked up with a constantly audio tone and needed the battery removed in order to switch it off. Useless.
Do NOT buy the TT Pro. Finis should be ashamed. Whoever is in charge of quality control for the TT pro should be sacked.

The Finis Tempo Trainer Pro is a nice simple timer that slips into a swim cap or under the band of your goggles. It has 3 buttons and a clock. The top button is for mode select and timer reset. The bottom two buttons are for the timer up/down and the on/off functions. Push the right button to turn it on. The top button is to select your mode and push both bottom buttons to turn the unit off.
It is really easy to set the unit up. Select the mode you want to try, set your desired time, push the reset button and you are off. The tempo trainer is advertised as a stroke tempo timer. I really like to use it as a lap tempo trainer. The instructions give you a lot of good advice on how to set the timer to suit your needs. It is also easy to figure it out for yourself. I don’t like to carry instructions around so I just do my own thing. Here are some of the things I like to do with the temp trainer:
Set the timer at 30 seconds then see how long it takes me to lap the timer. Take a 30 second break the repeat until I can’t catch it anymore.
Set the timer at 30 seconds, increase the speed by one second until I can’t keep up any more. Take a 30 second break then repeat.
Set the timer for 25 seconds then maintain the pace for a mile. If I want to see if I can do a sub 30 minute mile, I try to stay ahead of the timer.

I like the tempo trainer. It is a simple device that helps me vary my workouts. I tend to get into a rut with swim training. Having an easily changeable metronome in your ear encourages change.

Pros:
Fits well under the Finis Lightning goggle band and does not fall out
Very comfortable
The timer is very easy to reset while swimming
Easy to use while swimming
It encourages change to workouts
Instructions are not really required to get the thing working
Different beep tones, I prefer the triple beep
Easy to reset, when things go wrong
Replaceable battery
It floats

Cons:
It falls out of the headband of wide lens goggles
If it falls out, it can cause weird things to happen to the timer. The timer has to be turned off then back on, to reset the matter
If you have wide lens goggles, it can be troublesome to get in the band just right.
You have to be careful when using the cadence timer. It can cause short stroking, in an effort to keep up with the clock.

I did not feel the timer under the race goggles. When I was wearing wide goggles, I did not feel the timer until it fell off. Once I got it into a good position, I could not feel it on my head. This is one of those times, when simple is good.

I really like the thing. My pool is warm, which causes me to get lazy. The Tempo timer keeps me awake with a goal to be met for every length.

My daughter’s swim team requires this device for practices. First one failed after a few weeks. This was not a battery issue. The 2nd one lasted several months. Now I have to purchase a 3rd one! Wish there was a competitor’s product I could purchase instead.