These DO-214AA unidirectional protectors are constructed with a SIDACtor device and an integrated diode. They protect SLICs (Subscriber Line Interface Circuits) from damage during transient voltage activity and enable line cards to comply with various regulatory requirements including GR 1089, ITU K.20, K.21 and K.45, IEC 60950, UL 60950, and TIA-968-A (formerly known as FCC Part 68). For details of specific design criteria, see Figure 6.31 in Section 6, "Reference Designs" of this Telecom Design Guide).