I had a chance to see this in action at a local race. I was especially impressed at how easy it was to lay down the sensor - just a pair of parallel wires, instead of heavy rubber mats.
The downside is that the chips provide the power, and they are more expensive than mat-activated chips.
Also, the chips are worn around the ankle using a velcro strap. None of the runners appeared to mind.
I checked some select times later and found that they matched up just fine.
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