Review on Perixx PERIPRO-303 1.34 Inches Trackball - Pink Replacement Ball for M570, PERIMICE-517/520/717/720, and Other Compatible Trackball Mouse by Lisa Walton

EDIT: I've since found the original blue orb and I have to say the original is much better. The ones I bought as a replacement, sooo slow that I had to increase the cursor speed from 10 to 16 to get it working relatively well, but it stutters a bit and when someone tells me to clean the protrusions inside or the small laser clean inside, y I already have. He is still slow and stutters. I'm sticking with the original ball no matter how good the new one I spent $10 on is. ORIGINAL: I have an M570, I've had it for several years, I love this mouse. Trackball because my cat hit a mouse and the ball popped and who knows where went, bought it as a spare after reading that it was too small or didn't roll smoothly or anything but I personally haven't had any problems so it fits perfectly in the hole and looks better than the original blue ball! Luckily I haven't had any issues and for the price I would buy more of these for no other purpose than to change them with my mood lol. Ouch! Also, it comes in a very small box with foam which is good for keeping the ball in place. So if I ever find that other ball I have a nice little box to put it in so I can make it look better or pretty much cool! Very glad I found her!