These are the ones that the usb reciever fits in the base of the mouse when not in use
http://www.officemax.com/max/soluti...xpansionOID=-536879933&prodBlockOID=537422201
http://www.officemax.com/max/soluti...xpansionOID=-536879933&prodBlockOID=537417551
http://www.officemax.com/max/soluti...xpansionOID=-536879933&prodBlockOID=537422201
http://www.officemax.com/max/soluti...xpansionOID=-536879933&prodBlockOID=537417551