Blowscreen

A blowscreen was a component of Federation refitted starships in the 23rd century found within Jefferies tubes.

Aboard the USS Enterprise (NCC-1701-A) in 2287, Montgomery Scott directed James T. Kirk, Spock, and Leonard McCoy to take a right at the hydro vent and then left at the blowscreen to reach a turboshaft that led to the forward observation room.