A tanren bō (鍛錬棒) is a bat used in aikido for strength and suburi training.
By designating one corner as edge, an aikidoka can use it as an even heavier suburitō, practice suburi, kata, hasuji (edge-angle) and tomei (swing stopping)[clarification needed], and learn the bounce-back of the sword by practising against tenu-ichi, now typically a tyre stood upright on a concrete base.
As it is designed towards aikido and strength training, specifically for getting used to the weight of a heavy-handled object, it does not resemble a sword in shape, length, or mass.
Thus, unlike suburito, it is less effective for learning the katana's cut, and is not suited for contact with other swords.
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