Arclyte technologies performance - lithium batteries are designed for the highly mobile user that needs extra run-time without adding more weight. They deliver outstanding performance and exceptional reliability. Expect up to 20% longer battery life per charge and more charge cycles throughout the life of the battery. Compatible with the following laptop models: MacBook Pro 17-inch (MC226LL/A). Compatible with original/OEM part numbers: 661-5535, A1309.