Black Triple Roll

From the Feather Friendly® website:

"Feather Friendly® window markers are an easy-to-use scientifically proven solution for preventing bird collisions with glass surfaces. Feather Friendly® window markers are highly effective in making the area visible to birds and preventing deadly collisions while remaining unobtrusive to humans."
APPROVED BY:
FLAP Canada, Audubon, American Bird Conservatory

Black markers are recommended for fly-through areas like clear glass railing systems. Black can be much more visible on both sides of the glass, making them effective at preventing fly-through collisions.