A glider stopper is a Spartan logic circuit discovered by Paul Callahan in 1996. It allows a glider signal to pass through the circuit, leaving behind a beehive that can cleanly absorb a single glider from a perpendicular glider stream. Two optional glider outputs are also shown. The circuit can't be re-used until the beehive "bit" is cleared by the passage of at least one perpendicular input. The mechanism is related to the original Herschel receiver: replacing the east eater 1 with a pair of blocks produces an R-pentomino that is compatible with a following RF28B or RF48H converter.
A similar mechanism discovered more recently is shown in the beehive stopper article.