512MB PC-2700 200pin SO-DIMM internal memory module for the Apple computer systems shown in the table below. This unit is backwardly compatible with PC-2100 memory.
This is a used & tested part taken from a recycled Apple laptop.

Compatibility table
12" Aluminium PowerBook G4	All models
15" Aluminium PowerBook G4	All models except DDR2 version of 1.67GHz model (M9969LL/A) *
17" Aluminium PowerBook G4	All models except DDR2 version of 1.67GHz model (M9970LL/A) *
iBook G4, 12" & 14"	All models
15" iMac G4 (TFT screen)	1GHz model only
17" iMac G4 (TFT screen)	1.25GHz model only
20" iMac G4 (TFT screen)	1.25GHz model only

* Apple produced two variants of the 15" and 17" 1.67GHz PowerBooks; one using the DDR1 memory used by the rest of this range, and a later model using DDR2 memory. This memory will NOT work in the DDR2 models."