This is an original Vintage Military Airplane & Helicopter Electric RPM Indicator Gauge Instrument. It is marked type DO-36.  It is 3 1/4 x 3 1/4 x 4 inches. This item is being sold as a collectable. Payment must be received within 10 days of auction closing unless prior arrangements have been made. Buyer to pay shipping. AZ residents add 6.7% sales tax. If you have any questions please contact me via e-mail before bidding. Thank you for your interest in my auctions