WKF Heat Strips Fit the following: FE4A/5A, 40FKA, FV4A/B/C 002-006; FA4A/B, FB4A/B/C, FC4B/C, FB5A 018-070; PF1MN, PF4MN 018-061; FC4D, FY4A, FY5B, FA4C, FX4B/C 018-060; FH4A/B/C 001-004; FX4A 030-060, FX4D 019-061; FK4C/D 001-006 . Standard Features: - Elements protected by metal wrapper - Point Suspension element support system which eliminates hot spots to extend heater life - Time delay between steps which recycles on power interruption or brown-out - No off delay (a problem with sequencers) to increase SEER rating and prevents heating overshoot - Chatter and Rapid-cycle Resistant Contactors rated for 250,000 cycles - Rounded metal corners for safe handling. - Modular control plug for installation ease - ETL certified