---
title: fPreferredIOSize
framework: IOKit
role: symbol
role_heading: Instance Property
platforms: [driverkit 22.0+, Mac Catalyst 13.0+, macOS 10.13.1+]
path: iokit/scsicmd_inquiry_pagec0_data/2933387-fpreferrediosize
---

# fPreferredIOSize

## Declaration

```occ
UInt32 fPreferredIOSize;
```