Flat.

Secure and stable grip for better bike control
Center thickness: 16 mm
9 removable pins per side
Trail riding platform shape feels secure underfoot
Platform size: 101 x 96 mm
Resin composite pedal body with bushing construction axle
8 mm hexagon wrench mount
Weight: 394 g
139 g lighter than PD-GR500
Best combination with SHIMANO GR series shoes