To fit this replacement bulb to your Manta Ray Propagation Light, or other suitable lighting unit with a PL-L 4-Pin connection, first make sure that the lighting unit is turned off and unplugged from the mains socket to avoid unnecessary accidents. Gently pull the old bulb from the socket, being careful not to break the two supports that sit opposite the connector. The replacement bulb can then be fitted by carefully inserting it into the PL-L 4-Pin connector.