Features:
One of the most frequently used parts in Makeblock platform, compatible with all makeblock motion and Structure components.
Made from 6061 aluminum extrusion, anodized surface.
Threaded slot enables easy and flexible connection.
With holes on 16mm increments. and M4 thread holes on both ends.
Cross-sectional area 8x24mm, length 144mm. 
Sold in Packs of 4.