On March 10, Tolliver Tolles, also known as Thomas Towle, delivered to Alonzo Craig and Abigail Craig the following instrument, written by him in pencil:

For value received, I, Thomas Towle, promise to pay to the order of Alonzo Craig or Abigail Craig One Thousand Seventy-Five ($1,000.75) Dollars six months after my mother, Alma Tolles, dies with interest at the rate of 9 percent from date to maturity and after maturity at the rate of 93/4 percent.

I hereby waive the benefit of all laws exempting real or personal property from levy or sale. Is this instrument negotiable? Explain.