Bought for use with our PS2 and am delighted with them, no more wires to trip over. Our wired mikes were both breaking so these were a replacement, box did say PS3 only, but seller confirmed they are also PS2 compatible, and I can confirm this is true, instructions for PS2 set up came in the box.
What I got:
2 wireless singstar microphones
1 singstar detector (I'm sure this has a proper name but can't find it)
1 USB cable
4 x AA batteries (each mic takes 2 batteries)
1 red storage bag
So easy to set up for PS2, if you've used the wired microphones, just replace the current microphone connector with the new singstar detector using the USB port, put batteries in the microphones, turn on, and sing!
Other reviewers had mentioned a time lag with the wireless microphones but I think we had more problems with our wired mics, haven't found any lag with the wireless at all, in fact I think they are easier to use.
Each mic has a power switch - remember to check both are turned off after use or you will drain your batteries!