The Log Cabin 12 Inch Block Set contains both the Swirl and Feather 12 inch blocks.
The Feather Block is a digitized pattern for all computerized long arm systems, and is designed at 10 inches tall by 10 inches wide (25.4 cm x 25.4 cm).
The Swirl Block is a digitized pattern for all computerized long arm systems, and is designed at 11.5 inches tall by 11.5 inches wide (29.2 cm x 29.2 cm).
