Auxiliary handstamp, INSURED
Postal clerks applied "INSURED" markings to Fourth Class items when an insurance fee was paid. The procedures, charges, and requirements for insurance were specified in issues of the Postal Guide prior to 1970 and in the Domestic Mail Manual afterwards.
The handstamp shown was used for mailings at the lowest insurance threshold and did not require an insurance number to be entered into the oval. Higher insurance amounts required completion of an insurance form, for which a serial number was recorded. The handstamps used for those included "NO. _____________" within the oval for the insurance number to be hand-written in ink.