There are certain encumbrances against real property which are not true liens. One of these is the conditional bill of sale. This is an agreement for the sale of articles of personal property which are to be used in the improvement of real property under the terms of which title to the articles sold does not pass until the purchase price has been paid. The law in New York requires that the agreement must be filed in the office of the county recording officer at or before the delivery of the goods to the premises. If so filed, it is valid against the claims of other parties having interest in the realty, even though the articles may be affixed to the realty. Articles which are frequently the subject of these agreements are gas and coal ranges, boilers, elevators, lighting fixtures, etc. The agreement remains as effective notice usually for one year only unless refiled.