Touch Screen Digitizer Glass Compatible With iPod Touch 4th 4 4G Gen Blue
This is just the glass!!  On the 4G you must replace the glass and digitizer as a unit.  They do not seperate.  Watch any video on repairing the 4G and they all explain this (the 10 or so I watched, anyway).  It comes with cheap tools and no instructions on what each tool is supposed to be used for.  Do not waste your money.