View stu60xx stu65xx datasheet:

SURFACE MOUNT TRANSIENT STU606I - STU65G4 VOLTAGE SUPPRESSOR VBR : 6.8 - 440 Volts SMB (DO-214AA) PPK : 600 Watts 1.1 ± 0.3 FEATURES : * 600W surge capability at 1ms * Excellent clamping capability 0.22 ± 0.07 * Low zener impedance 2.0 ± 0.1 2.3 ± 0.2 * Fast response time : typically less 3.6 ± 0.15 then 1.0 ps from 0 volt to VBR(min.) * Typical IR less then 1µA above 10V * Pb / RoHS Free Dimensions in millimeter MECHANICAL DATA * Case : SMB Molded plastic * Epoxy : UL94V-O rate flame retardant * Lead : Lead Formed for Surface Mount * Polarity : Color band denotes cathode end except Bipolar. * Mounting position : Any * Weight : 0.093 grams DEVICES FOR BIPOLAR APPLICATIONS For bi-directional altered the third letter of type from "U" to be "B". Electric