In addition to the CD 140 insulators used by the transit authority in Boston that were along short stretches of downtown Boston tunnels, many of these insulators were also used along streets, etc. Some were on wood poles, others on metal ones. All are long gone owing to the removal of many trolley routes in the city and pole/crossarm upgrades through the many decades.

The "coated" insulators seen here probably were painted when the crossarm (and pole?) were.

Click "Previous" for an overall view of this pole and the trolley station that was adjacent to it.