A finger heart rate monitor (also called finger wrap heart rate monitor) can provide continuous heart rate monitoring without the use of chest straps. This is quite unusual because most strapless heart rate monitors cannot give you real-time on-the-spot heart rate monitoring. In those other monitors you have to stop your exercise, put your fingers on the wrist watch for a few seconds, take the readings and then restart your exercise. It is quite cumbersome really.
However, a finger HRM does not require you to do that. It monitors your pulses at the tip of your finger continuously. You can keep the benefits of a chest strap heart rate monitor (i.e. continuous monitoring) without the use of a chest strap. Interference from outside sources is also no longer an issue. The downside is that it is probably not as accurate as the chest strap ones which uses electrocardiogram to measure heart rates. As in everything in life, there is a trade off.
There are very few of these types of HRM around and it is certainly not a common sight.
Below is a list of finger HRMs that have been featured on this web site. It is not an exhaustive list.
Of the two, Mark of Fitness MF-180 have our vote as the better buy. The MF-180 has a higher quality feel to it and unlike the PowerGlove, it does not look like an experimental construction straight out of a lab. On Amazon, the users give the MF-180 much better reviews compared to the PowerGlove HRM.
Note: There is also a product known as Beurer PM100 by a German company. It is very similar to the MF-180 with exactly the same specs. In fact it looks like it is the same monitor with a different branding and using different fabric for the glove. The Beurer PM100 is not generally available in the US though, but if you have been looking for it, then simply check out the MF-180.