There's this thing in the internet about Microsoft Intellimouse and Optical Sensors. I saw a local online vendor in our country selling them(used) for around US$ 5.50 each or US$ 4.50 for every bulk of 10 pieces and above. I decided to get three of them.
All of them are still in good condition and functional, and needs some cleaning after I bought. It has a bit of discoloration or yellowing - which is common with white or light colored unprotected ABS plastics when exposed to UV over time.
Program-specific settings is also available. If certain functions or key combinations is not available in the options, you can customize your own macro.
The IntelliMouse series is often credited for: Microsoft being one of the first mouse vendors to introduce a scroll wheel, an optical mouse, and dedicated forward- and back-buttons on the side of the mouse for easier web-browsing.
Even with all the praise for this mouse, it still can't replace my G500s as my daily driver, because of the following:
1) The mouse is light. I like it to have some weight, to have a balance speed and control.
2) Left and right side buttons are soft and mushy. It makes me feel not to use this buttons often.
3) Very low sensitivity(DPI). Not very useful on my 1080p display. I always use my G500s on this with 3200 DPI and 500 MHz polling rate to minimize the needed mouse travel.
4) Materials used could have been better. Side buttons paint coat will fade with often use. The white body shell is not covered with UV-resistant coating and will suffer discoloration or yellowing over time.
After all of that, it's still cool to own one of these mice.