Ulf Norlinger Oct 20, 2009:

Fjädersprintens (bra förslag!) design(?), se nedan "The clip pin can have a knob on one end and a spring-loaded ball partly protruding from a side of the other end. This allows quick adjustment by simply pulling the clip pin out, sliding the outer tube to a new position where holes in the inner and outer tube are aligned, and pushing the clip pin through the aligned holes. The spring-loaded ball retains the clip pin in the holes."