This set of 10 O-Rings (Very Small) is suitable for Mutoh RJ-800 printers. This is the original Mutoh part (number KY-40487). These o-rings have an inner diameter of 1.5mm and an outter diameter of 3.5mm.
 
Printer compatibility
Mutoh RJ-4000 (Falcon)
Mutoh RJ-4100 (Falcon)
Mutoh RJ-4100P (Falcon Plus)
Mutoh RJ-6100-46 (Falcon)
Mutoh RJ-6100-46+ (Falcon Plus)
Mutoh RJ-6100-54 (Falcon)
Mutoh RJ-6100-54+ (Falcon Plus)
Mutoh RJ-6100-62 (Falcon)
Mutoh RJ-6100-62+ (Falcon Plus)
Mutoh RJ-800
Mutoh RJ-8000-50 (Falcon II)
Mutoh RJ-8000-64 (Falcon II)
Mutoh RJ-8000-87 (Falcon II)
Mutoh RJ-801