Suction Cup Mount for GPS Antenna
This unit is designed for mounting a small GPS antenna to a car windshield but it also works great on a sailplane canopy.  It is a thin steel plate with mounting holes for a variety of GPS antennas.  It includes 2 small mounting screws for use with the GPS antenna.  Many GPS antennas have built-in magnets which work great without any need for mounting screws.  Velcro would also work great.  It is easy to bend the unit to the desired angle.  The 4 suction cups hold onto the mounting surface well - provided you clean the surface and wet the suction cups before mounting.

This unit is designed to hold a light load such as a GPS antenna.  It is probably not strong enough to support anything much larger.

At least one customer replaced the suction cups with clear 3M Dual Lock.  The 3M Dual Lock hold more securely than the included suction cups.

Dimensions
Top mounting surface: 2.60 x 2.64 inches (66 x 67 mm)
Suction Cup surface: 1.6 x 1.6 inches (41 x 41 mm)
Suction Cup Diameter: 0.83 inches (21 mm)