A SCSI Peripheral Device Type describes the capabilities provided by a

SCSI Small Computer System Interface (SCSI, ) is a set of standards for physically connecting and transferring data between computers and peripheral devices. The SCSI standards define commands, protocols, electrical, optical and logical interface ...

device. It is a five-bit field in the first byte returned in response to an INQUIRY

SCSI command In SCSI computer storage, computers and storage devices use a client-server model of communication. The computer is a client which requests the storage device to perform a service, e.g., to read or write data. The SCSI command architecture was or ...

.Draft of SCSI Primary Commands - 4 (SPC-4 r36d), section 6.6.2 - Standard INQUIRY data
Defined values are:

References

SCSI {{compu-hardware-stub