Early 1960s Inter-Mark Cipher Sentinel Hollow Body Guitar (MIJ)Early 1960s Inter Mark Cipher Sentinel Hollow Body Guitar (MIJ) A short lived guitar brand from the early 1960s, Cipher guitars were manufactured by Shinko Gakki in Tatsuno and distributed by Inter Mark corporation. The Shinko Gakki factory also made organs and pianos! Their guitars are super quirky in their designs and are a great example of 60s Japanese woodworking and craftsmanship. The Sentinel is a fully hollow jazz style guitar that has a large,