I have not seen a padlock like this one before, which might explain the high price it went for.
This is an antique brass pad lock.
It is marked "Detective Lock Pat June 14 92 USA"
Good condition for its age - could use polishing.
Very unusual flat key hole.
We don't have the key.
Measures approx 3.25 long by 2 1/8" wide by 1/2" thick. - eBay (2 June 09)
This padlock had a high bid of $685.89 (Plus $4.95 Shipping).