Up until 1967, the Marshall 1959 Super Lead guitar amp was powered by four KT66 tubes. This was the basis for the for the iconic 100 watt "Marshall Stack."
Illustrated and designed by Serifs & Whiskey studio. 
These posters are nice and big, measuring 13" x 19". Printed on high-quality 100lb Cougar cover stock that gives it a nice hefty feel. Easily drops into a standard frame.