Ring Beam Units are small, swiveling turrets installed in the BOTTLE SHIP's Bioweapon Research Center in Metroid: Other M, where large numbers of the machines have been installed in a few corridors leading to Room MW. They are completely indestructible, and every few seconds will fire Rinka directly at Samus Aran. A similar turret appeared in Metroid Prime 3: Corruption. During the battle with Aurora Unit 313, there are mechanisms located on the floor that shoot red projectiles quite similar to Rinkas. Ring Beam Units are very similar to the Cannons used to defend Mother Brain in Tourian.