Casio CTK-4000 Premium Keyboard Pack with Power Supply, Keyboard Stand and Professional Closed Cup Stereo Headphones : Musical Instruments - Amazon.com
Casio CTK-4000 Keyboard Piano Service Manual (Pages: 26) | eBay
CTK-4000 - Standard Keyboards - Electronic Musical Instruments - CASIO
Amazon.com: Casio CTK-4000 Personal Keyboard, 61-Key, with MP3 Connection, 10 Second Sampling, and Digital Effects : Musical Instruments