Oregon Scientific SE128 heart rate monitor is a basic heart rate monitor. It is a slightly more advanced model than the SE200, even though normally the numeric order would suggest otherwise.
An audio alarm (if switched on) and visual indicators alert you when you are training above or below your heart rate zone limits.
Calories burnt
Stop watch
Basic time keeping: Time, date and alarm
Backlight
Wireless heart rate monitor (ECG accurate) with an analogue chest strap transmitter and a wrist watch receiver
Keypad lock on wrist watch so that its operations are not affected by the accidental pushing of buttons
Battery for chest strap transmitter is user-replaceable.
It can work with gym equipment (e.g. treadmills) capable of picking up your transmitter's signals to show your heart rate on the equipment's display panel
The features in bold above denote the features found in SE128 but not in SE200.
The SE128 is missing the following basic features: Average heart rate, maximum heart rate of exercise session.
Summary
The Oregon Scientific SE128 is a simple heart rate monitor for beginning heart rate monitor users. It is very similar to the Oregon Scientific HR102 and the Oregon Scientific SE200 in terms of features. All three are entry level heart rate monitors with standard features like heart rate training zone with alarm. The Oregon SE128, however, has the additional calories burnt feature for weight loss and management.