Although these modules are not IBM originals they are guaranteed to be 100% compatible with your thinkpad and meet or exceed the specifications from the manufacturer. IBM PART# 10K0034 Comaptible 1GB PC2100 DDR SO-DIMM $120.00 IBM PART# 31P9834 Compatible 1GB PC2700 DDR SO-DIMM $125.00 IBM PART# 10K0032 Compatible 512MB PC2100 DDR SO-DIMM $55.00 IBM PART# 31P9832 Compatible 512MB PC2700 DDR SO-DIMM $54.00 IBM PART# 10K0030 Compatible 256MB PC2100 DDR SO-DIMM $27.00 IBM PART# 31P9830 Compatible 256MB PC2700 DDR SO-DIMM $28.00 IBM PART# 10K0028 Compatible 128MB PC2100 DDR SO-DIMM $15.00 IBM PART# 31P9828 Compatible 128MB PC2700 DDR SO-DIMM $16.00 IBM PART# 73P3840 Compatible 512MB PC2-4200 DDR2 SO-DIMM $49.00 IBM PART# 73P3844 Compatible 1GB PC2-4200 DDR2 SO-DIMM $98.00