Billable expense without a cost

Hmm, thanks for the suggestion(s) however the Sales Receipts option doesn't seem to be a fit since that appears to be for a payment rec'd for service or items . . . I need an option to be able to enter the client's cost of the rental when it happens so when it's time to create the invoice, the rental charge is pulled in to the client's invoice but without creating an expense since the trailer is currently paid for, it's a charge for the use of our dump trailer.  Still seeking an entry solution.    

Thanks for your response . . . yes, there is not an incurred cost or expense for the rental, nor do we invoice or get paid at the time the rental occurs.  We typically create a progress billing invoice(s) for our clients with billable charges incurred, say, over a month or a specific phase, then the client's billing invoice is created from the entered billable charges (detailed on the invoice) with our mark up, for an amount due.  I'm hoping to find out how to enter that charge so that it's available at the time of billing, but something tells me I will need to keep track of dates the rental(s) occurred separately somehow and then when it's time to bill, the charge can then be included in the invoice as a rental charge (set up as a service).  Does that make sense?  I was just hoping there was a way to enter the charge at time of use so that it could then be pulled in to a future billing invoice . . .