The Arri X-Fly 20 12.5' Friction Pantograph comes completely factory assembled with a choice of optional adapters at the top and bottom. The double scissors mechanism provides the rigidity to stabilize loads of up to 40 lbs (18.14 kg) using optional counter balance springs. Clips to attach a power cord for a lighting circuit are included. The patented built in friction brake with its colored notched ring allows you to adjust the friction to ensure the load will float once set into position, but will move smoothly up and down when necessary. Loads over 8.8 lbs (4.0 kg) require separate purchase of counter balance springs.