A Japanese Maruho soroban, which is an abacus used in Japan for speed counting. Some Japanese are extremely adept with soroban and learn, through its use, to do huge calculations very rapidly, either using the soroban or, through much practise on them, by visualising one in their heads. 
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Maruho abacus are high quality and have long history.
It has initials scratched onto it - see photo. A rub with a walnut  or a rub of brown shoe polish would likely hide that well.
Made in Japan
In Japan, studying abacus is believed to help strengthen one's ability to do mental calculations. It is impressive to see them in use.
To see  an impressive YouTube video of soroban abacus in use, click HERE. You can also find soroban use lessons on YouTube.
 
Condition: 
Used - in excellent condition. This one has initials scratched into the back, rubbing over them with a walnut will darken the wood, making them much more discreet, or try bown shoe polish

Measurements:
38.6 x 6.35 x 1.5cm
Weight : 205g
 
 
 
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xi281/03/12