[Natural (NA) 1.25mm]

[Black (BK)   1.25mm]

[Natural (NA) 0.5 inches (1.30 mm)]

[Black (BK)   1.30mm]

Emphasizes on striking feel with a high hold and proper assist function; Kaiishima structure (19 islands) x Multi-filament x LFS (low friction silicone resin) coating.
BT adopts 19 Islands of Kaijima structure, but this is a structure that feels softer than the core itself, and it also has a multi-filament and LFS coating for added hold and assistance performance (it is easy to fly without force) + a lot of holding feeling.