Black Widow Z5 Car Security System With Remote Start The Z5 comes with one BWST5 and one BWST4 transmitter. The Z5 will learn up to 4 transmitters per system (2-way or 1-way). Black Widow's transmitters and receivers all meet FCC's requirements to operate in the U.S.A. The BWST5 is a 5-button two-way transmitter that offers total control over the Z 5 system and gives your customer real time notification of the systems status up to 3000 feet away! The BWST5 has large easy to read icons on the display and related icon buttons that make it easy to use. The BWST4 is a 1-way 4-button, water resistant transmitter and has a range of up to 1000 feet! The Z1 system offers the exact same features as the Z 5 but with two BWST4 transmitters. These transmitters offer up to 1000 feet of range and provide your customer total control of their vehicle's security and remote start system.