Alive board ed
The Alive board has two parts connected with a flexible intermediate piece. 2 wheels are mounted inline on the front and rear parts. So the board has 4 wheels. The flexible spacer allows you to place the front part perpendicular to the back part and thus create very small circles. It is a board that allows you to make extreme turns, but it is less stable than a caster board. Also check out www.aliveboard.net