# kIOPropertyBytesPerPhysicalSectorKey ``` #define kIOPropertyBytesPerPhysicalSectorKey ``` ## Discussion This key is used to define the number of heads for a particular medium. Requirement: Mandatory element of the Rigid Disk Geometry dictionary. Example: ```objc Device Characteristics Vendor Name Apple Product Name iPod Product Revision Level 1.0 Rigid Disk Geometry Sector Count per Track 12345 Head Count 12 Cylinder Count 12345 Bytes per Physical Sector 512 ``` --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)