Garmin HRM-Fit - The HRM-Fit chest strap is specially designed for women. It easily attaches to a medium or strong support sports bra and provides accurate heart rate data. In addition, running efficiency values are recorded to help you improve your form.
General:
Dimensions: 33.5 x 3.3 x 1.7 cm
Module size: 31 x 55.5 x 14.2 mm (W x H x D)
Strap length: not applicable
Weight: 53 g
Water resistance: 3 ATM
Battery: CR2032
Battery life: Up to 12 months (Usage: 1 hour per day)