Ah, right, I wasn't able to show you before. Here-

[Luca stands up and moves past Cabanela, going to a nearby aisle where he can crouch down. Then he pulls out the box of chalk, removes a piece of chalk from it, and draws a small circle with some swirls throughout it.]

This is an array. Cyclists typically need help maintaining a sfeer, and this provides stabilization. The design also helps focus a sfeer towards a particular type of magic. This one, for example, is used for wind control.