4GB DDR2 800MHz SODIMMs for Macs

Technical Specifications:

4GB PC2-6400, DDR2-800, 800Mhz, Latency 5-5-5 , Non-ECC, Unbuffered, 1.8V, 200pin SO-DIMM (Small Outline Dual Inline Memory Module) format. This module is compatible with the latest Apple Firmware.

The installation video will help on how to install iMac 8,1 memory on your machine:

If you need more product details about how to install iMac 8,1 memory on your machine, you can refer to the Apple's installation guide (PDF.)