The swirly grids are an aluminum-only PCB, made up of the aluminum backing with black soldermask on the front along with a silkscreen.

The 10x5 grid is 3" x 6" altogether.

Swirly grid features:

• White lines to separate each square in the grid
• The coordinates of each square within the grid, printed in the center of each square
• Each square is 0.6" x 0.6"
• Holes or slots every 0.2"
• Boards with mounting hole spacing that is a multiple of 0.1" will mount to the grid
• Compatible with Feathers, FeatherWings, and most STEMMA QT breakout boards
• Drill holes are 0.1" (2.45mm) diameter
• Slots are 0.11" x 0.3" (2.75mm x 7.5mm)
• If desired, easy to customise by cutting, drilling, machining, bending the aluminum