Logitech M720 Triathlon is different from other mices, because it can be simultaneously connected to up to three devices, by pressing the profile key. It has the Hyper-Fast Scrolling technology, invented by Logitech long time ago, which is activated by pressing the key above the wheel.
Ergonomically, it's designed for right-handers, rubbed, and feels great in hand. There are 8 keys, a key from the left side can be programmed for different actions and it's silent. You can adjust the function of each key, replace the left and right keys and adjust the pointer speed.
It connects by Unifying Receiver (miniature USB chip) or Bluetooth. It's powered by a standard AA battery, which can withstand up to 24 months. In addition to the power key, an autosleep option is built-in, which means that it will shut down if not in use for some time.
The design of both Silent mice is classic, and somehow the biggest advantage is that these mice will not wear down so quickly, as opposed to other, cheaper ones
Logitech Silent mice are definitely something you have to try. Smaller, M220 Silent, and slightly larger and thus more convenient M330 Silent Plus have two silent keys and central silent wheel. Though they're not exactly silent, but they aren't so loud as onconventional mice. They're fed by standard AA batteries and have an autosleep function.
M220 is slightly smaller and connects to a Wi-Fi by Logitech Unified Receiver in the 10-meter range, as well as Triathlon, and M330. It's adjusted for left or right handed, but if you have larger hands, this model will probably be too small. It appears to be plastic and not too solid, unlike the M330 Silent Plus.
Silent M330 Plus is ergonomically adapted for right-handed, it's rubbed, and has enhanced grip for the thumb. It can be connected using Unifying Receiver, like Triathlon, but with it, you get a regular receiver, just like with the smaller M220.
Prices of these mice range from around $25 for M220 Silent, $30 for M330 Silent Plus, and 50 bucks for M720 Triathlon. You can see all their characterstics in the video below.
More about Logitech.