it’s a little complicated because the case and PCB screws are all packed together with the PCB and terminal blocks. To provide a ‘no enclosure’ option would require taking these screws out. The OSPis are all packaged in batches and sealed in anti-static bag, Since it’s difficult to predict how many ‘no-enclosure’ orders there will be, we’ve decided to just remove this option to reduce the overhead on our side. If you do not need the enclosure, you can contact us directly and we can make adjustment accordingly. We just don’t want to provide this as a public option. Thanks for understanding.