A high-speed capable device that has different device information for full-speed and high-speed must have a Device Qualifier Descriptor (USB_DEVICE_QUALIFIER_DESCRIPTOR). For example, if the device is currently operating at full-speed, the Device Qualifier returns information about how it would operate at high-speed and vice-versa.

The fields for the vendor, product, device, manufacturer, and serial number are not included. This information is constant for a device regardless of the supported speeds.

If a full-speed only device receives a GetDescriptor() request for a device_qualifier, it must respond with a request error. Then, the host must not make a request for an other_speed_configuration descriptor.

Offset	Field	Type	Size	Value	Description
0	bLength	uint8_t	1	Number	Size of this descriptor in bytes.
1	bDescriptorType	uint8_t	1	Constant	Device Qualifier Descriptor Type = 6.
2	bcdUSB	uint16_t	2	BCD	USB Specification Release Number in Binary-Coded Decimal (i.e., 2.10 is 210h). This field identifies the release of the USB Specification with which the device and its descriptors are compliant. At least V2.00 is required to use this descriptor.
4	bDeviceClass	uint8_t	1	Class	Class code (assigned by the USB-IF). If this field is reset to zero, each interface within a configuration specifies its own class information and the various interfaces operate independently. set to a value between 1 and FEh, the device supports different class specifications on different interfaces and the interfaces may not operate independently. This value identifies the class definition used for the aggregate interfaces. If this field is set to FFh, the device class is vendor specific.
5	bDeviceSubClass	uint8_t	1	SubClass	Subclass code (assigned by the USB-IF). These codes are qualified by the value of the bDeviceClass field. If bDeviceClass is reset to zero, this field must also be reset to zero. not set to FFh, all values are reserved for assignment by the USB-IF.
6	bDeviceProtocol	uint8_t	1	Protocol	Protocol code (assigned by the USB-IF). These codes are qualified by the values of the bDeviceClass and bDeviceSubClass fields. If a device supports class-specific protocols on a device basis as opposed to an interface basis, this code identifies the protocols that the device uses as defined by the specification of the device class. If this field is reset to zero, the device does not use class-specific protocols on a device basis. However, it may use class-specific protocols on an interface basis. set to FFh, the device uses a vendor specific protocol on a device basis.
7	bMaxPacketSize0	uint8_t	1	Number	Maximum packet size for other speed.
8	bNumConfigurations	uint8_t	1	Number	Number of other-speed configurations.
9	bReserved	uint8_t	1	Zero	Reserved for future use, must be zero.