The 2 hole base studs with fit the sockets and plates we have for sale. 

Overall length 27mm (Edge of base to edge)
Overall height 17mm 
Distance from hole centre to hole centre 18mm
Hole diameter 4mm
Neck length - 10mm to indent / 15mm to tip
Nickel plated brass

These fasteners suit all sorts of boat canopy covers, gazebo curtains and other leather / upholstery work