The support plate protecting Enterprise's osmotic filters
A support plate was a glass-like structure used aboard 22nd century Starfleet vessels for the purpose of protecting various ship's systems and equipment.
In 2152, Doctor Phlox was required to remove a support plate in order to gain access to Enterprise NX-01's osmotic filters, which he needed to purge before connecting the ship's central ventilation to the carbon dioxide tanks. He performed this action by inserting two fingers into the upper holes of the plate, and then tapping two solenoids simultaneously, causing it to retract. (ENT: "The Crossing")