Does the Keiser bike have a heart rate readout built in? If so then you don't need the Polar wrist unit, only the transmitter. You can purchase only a transmitter and chest strap and save some money that way.
The Polar FT7 wrist unit comes with a Polar H1 heart rate transmitter and chest strap. The FT7 and H1 are older units and have been replaced by newer models.
I don't know what the Keiser bike uses but I have a newer Polar H7 heart rate transmitter/strap which uses bluetooth. The treadmills and exercise bikes at the gym pick it up as soon as I start to exercise.
-Tim-