The Leangle Buckle (レンゲルバカル Rengeru Bakaru) is a transformation device that Mutsuki Kamijo uses to become Kamen Rider Leangle. It was the second Rider System produced by Isaka/Peacock Undead with the aid of the B.O.A.R.D. scientists under his control (Chief Kei Karasuma among them). Its designed specifically for compatibility with the ♣A: "Change Spider" Rouse Card. This Rider System model utilizes the "Open Up" mechanism, to scan the Category-Ace Rouse Card; producing a transformation screen that attracts to the Rider (as opposed to the earlier systems which produced stationary screens). Coincidentally, the transformation screen itself can act as a deflective wall against assaults.