View stb606i stb65g4 series datasheet:

SURFACE MOUNT STB606I - STB65G4 BIDIRECTIONAL TRANSIENT VOLTAGE SUPPRESSOR VBR : 6.8 - 440 Volts PPK : 600 Watts SMB (DO-214AA) FEATURES : 1.1 ± 0.3 * 600W surge capability at 1ms * Excellent clamping capability * Low zener impedance 0.22 ± 0.07 2.0 ± 0.1 * Fast response time : typically less 2.3 ± 0.2 3.6 ± 0.15 then 1.0 ps from 0 volt to VBR(min.) * Typical IR less then 1µA above 10V * Pb / RoHS Free MECHANICAL DATA Dimensions in millimeter * Case : SMB Molded plastic * Epoxy : UL94V-O rate flame retardant * Lead : Lead Formed for Surface Mount * Mounting position : Any * Weight : 0.093 grams DEVICES FOR UNIPOLAR APPLICATIONS For Uni-directional altered the third letter of type from "B" to be "U". Electrical characteristics apply in both directions