A contract of sale under which a seller bills a customer but retains physical possession of the goods until it is transferred to the customer at a future date. Goods are excluded from the seller's inventory and included in the buyer's inventory upon billing provided: (a) The customer has requested for the arrangement, (b) The goods are identified separately as belonging to the customer, (c) The goods are available for immediate transfer to the customer, (d) The seller cannot use the goods or sell them to another customer.