Double Take Horizontal Split Mount
https://us.adventurespec.com/shop/dtm-horizontalsplitmount-double-take-horizontal-split-mount-387
https://us.adventurespec.com/web/image/product.template/387/image_1920?unique=3cb3181
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10mm x 1.25 threaded mirror mount on horizontal split clamp. Allows mounting on clutch or brake master cylinder for most KTMs, and many Beta, etc.