Hgst travelstar 25 7mm 500gb 54k hdd travelstar z5k500 is the second generation 7mm 5400 rpm 25 inch hard drive from hgst with capacities ranging from 250gb to 500gb and the second generation advanced format drive advanced format increases the physical sector size on hdds from 512 bytes to 4 096 4k bytes which improves drive capacities and error correction capabilities the 500gb per platter one disk models are designed as a direct replacement for standard 95mm hdds for use in not