Flush Button
From Amazon
GROHE Even - Flush Plate for Concealed GD2 Cisterns (Water-Saving, Dual Flush with Start-and-Stop Activation for Pneumatic Drop Valve AV1, Easy to Install), Size 156 x 197 mm, Phantom Black, 38966KF0
Wayfair
Even Two-Touch Control Panel, Anti-Fingerprint Technology, Matte Black (38966KF0)