The Von Duprin 47447541 Modular HD-QEL Motorized Latch Retraction Conversion Kit is made for use in 36 inches or 48 inches applications. It is compatible with the 22 Series produced after January first, 2022. This kit allows the latch bolt to retract momentarily using access control systems or to retract for longer periods, replacing mechanical dogging. The QEL board includes electronic LEDs that indicate errors.