The IDC 50 connector is a 50-pin, 8-bit SCSI "header" connector used for internal-type ribbon cables. It is also known as the "Alterative 2" connector. It has parallel 25-pin rows and resembles an older ATA/IDE drive cable, except that it is wider and has more pins.
The HPDB 68 connector is a 68-pin, 16-bit SCSI-2 connector, used for both internal and external connections (plastic for internal and metal for external). It has parallel 34-pin rows, but has the pins much closer together and is therefore narrower than the IDC 50 connector. It is also known as the HD68, Mini D68, or "Alternative 3" connector.
This adapter has a female IDC-50 connector on one side and a female HPDB 68 connector on the side. Made of plastic, it is suitable for both internal and external applications.