tender for set of insulating rings (part of ioh / poh kit) of tap changer comprising of - (1) insulating ring(inner)=1 no. as per m/s. btis part no. s1218 or g1218 of m/s aal or rdsos drg. no. skel - 4661(alt.-1).(2) insulating ring (outer)=1 no. as per m/s. btis part no.- s1219 or g1219 of m/s aal or rdsos drg. no.-skel - 4661(alt.-1).