Using high-density, lithium-ion batteries, the device, including its harness, weighs 20 pounds and can propel a person up an anchored rope at 10 feet per second, Ball said.

采用高密度、锂离子电池、仪器，包括其利用，重达20磅，一个人就可以了锚绳10英尺每秒，球说。

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For all the sport's complex strategies and mind games, there is a visceral appeal in seeing a piece of wood propel a leather ball 400 feet over a fence and watching the batter trot confidently around the bases.

ECONOMIST: A legendary distraction