捕手用 送信機
https://cdn--media-theathletic-com.cdn.ampproject.org/i/s/cdn-media.theathletic.com/cdn-cgi/image/width=700,height=466/YSpmCwV3skV2_YSpmCwV3skV2_7ygG0DRIsa55_original_1440x1087.png
https://www-tsn-ca.cdn.ampproject.org/ii/w820/s/www.tsn.ca/polopoly_fs/1.1780286.1649008530!/fileimage/httpImage/image.jpg_gen/derivatives/landscape_620/pitch-com.jpg
http://pbs.twimg.com/media/FPoSCpjWYAU_eFF.jpg
http://pbs.twimg.com/media/FPlpg17XEAE4bgh.jpg
投手/野手用 受信機
http://pbs.twimg.com/media/FPi7BviVEAAHPtW.jpg
http://pbs.twimg.com/media/FPmSR_RVIAI6dWk.png
捕手の送ったサインが音声で伝達される
MLB Approves PitchCom to Limit Sign Stealing - The New York Times
https://www.nytimes.com/2022/04/05/sports/baseball/pitchcom-sign-stealing.html
