It is a part for BOT-1221-BK.
A strap of this length is included at the time of purchase.
 
■ Size
For BOT-1221-BK

Trial boots (BOT-1221-BK) General purpose. It was

■ Color
BLACK

■ Attached contents
Strap short type x 2
Strap long type x 1
Buckle x 3
Mounting screws

This item is packaged.
Some parts are not sold separately.