Can you help me with this case in the aspect of a negotiable instrument?

John goes to a bar.Harry starts to talk to him about a car he has for sale.John tells him he wishes he could buy the car but does not have that much cash.Harry tells John he can make payments over the next year.Harry writes on a napkin John shall pay me $100.00 per month for 12 months starting December 1, 2018.They both sign and date the napkin.

Discuss whether this is a negotiable instrument.Defend your position. Ensure you discuss each element of negotiability.