The Imprint Type Lesher Dollars have a blank area at the bottom of the obverse where Lesher could punch in the name of an advertiser and perhaps a serial number for the coin. Normally, the Imprint Type Lesher Dollars that appear on the market have these punches in place (examples include the names of Slusher. White, Boyd Park, etc). Occasionally an example appears that never received a punch of any sort; others show a serial number; and more rarely, one can see a merchant's name without a serial number.
The type referred to here is the Imprint type without an imprint, but with a serial number. In effect, these were blanks waiting for an imprint that never took place. It may be possible to associate the ones with serial numbers to the merchants where ranges are known. However, we'll leave that to more serious researchers. For collectors, this is a must -have type.