Review on Perixx PERIPRO-303 X4A Trackball With 1.34-Inch Replacement Ball For Perimice And M570 - 4-In-1 Multi-Color Trackball In Red, Purple, Pink, And Lavender With Stylish Storage Box by Kelz Dixon

I have both Logitech M570 and Elecom EX-6 trackballs (1st generation) and purchased this replacement ball to improve the tracking on the Elecom EX-6. After experimenting with this ball in both the M570 and EX-6, my observations were that this ball performed identically to the blue M570 trackball in both devices.Note: the M570 trackball is commonly suggested as an upgrade to the stock EX-6 trackball.my observation bears this out as both balls performed better than the grey trackball standard on the EX-6.So, to summarize:If you have a Logitech M570, this ball is functionally equivalent to the stock M570 blue ball. If you need a replacement ball and don't want to spend $20 on the Logitech one (why would you when you can purchase a new M570 for $24?), this one is half the price.If you have an EX-6, I would immediately replace the standard ball with this one for improved tracking. One caveat is that my EX-6 is a 1st generation EX-6 (ELECOM M-XT3); it appear that the version now being sold is the 3rd generation (ELECOM M-XT3), so your mileage may vary. It appears, however, that the M-XT3 is still using the same trackball as the M-XT1 and several reviews on that device suggest that the standard ball does not track as well as the M570 ball.