Thanks for interest our product.
The two models have different application.
GH-625: Personal Trainning, 5KHz HRM technology
GH-505: Personal and Mutisport Training, 2.4GHz technology for HRM, Cadence, Speed sensors.
Due to Display of GH-505 encountered stock shortage and reliability problem, so we hold the production until the issue be solved.
Thanks Geoffrey. And when do you think the problem will be solved?? No idea? And what is the difference between 5KHz and 2.4GHz?
We will expect 2011 Q1 to finish. 5KHz is polar compatible and price cheaper, but it is easy to get interferred by noise. 2.4GHz can be adapted to the any 2.4G ANT standard protocol accessories. But higher price.