Acer Altos 1100 Series User Manual page 109

The LVD SCSI hot-swap cage includes a hot plug SCA single-ended backplane,
LED board, and the hard drive cage itself. It supports three 1-inch SCA-II SCSI
hard drives in one channel with active terminator built-in. The SCA II connector
design allows for the addition and removal of SCSI drives without shutting down
the system.