Yamaha YRA 901 Alto-blockflöjter F1 Brun

Arched Windway
It has a slight resistance when you play for better breath control which gives greater tonal expressivity and projection.

Castellowood
A softer wood with a beautiful warm tone, good for expressing subtle musical nuances. Though it is not technically a boxwood, it is commonly referred to as "Castello　Boxwood".　(Gravity after drying approx. 0.7)