Having the right tools, is half the work done. The Point-7 extensions are based on a very simple indestructible system that is quick and simple to use and allows for effortless downhaul, even on very big sails. 
The pulley and cleat system is attached directly onto the aluminum tubing, with no crossing lines. With the brass rollers, downhaul efforts are reduced to the absolute minimum. 

Quick functionality points on the base system: 

Double inverted XXL pulleys to save lots of power from pulling downhaul.

Easy clean free threading through pulley to use gravity to insert the rope.

Free cleat to no rope friction when down hauling.

Rigs on both side as cleat is on the side of the pulley system.

The 2XXL pulleys allow to downhaul the sail with much less power than normal wheel size. More logic to insert the rope in the pulleys. The cleat has no bridge on top to guide the rope when down hauling. This gives much more freedom to pull, less friction, and when connecting the 2 characteristics, it makes the down hauling much lighter and easier. There is no need to have cleats on both sides for rigging on port tack or starboard tack as the cleat is free and easy to lock the rope on both tacks.

The extension tubes are made with strong T8 grade aluminum and are available in lengths of 32 cm/48 cm with adjustment increments for every 2cm. The extensions can be sailed at the full 32cm or 48cm extension heights and are supplied with the original Marlow 3.8mm Formuline rope.  

Sizes available: SDM 32, SDM 48

Click here for detailed information about Point-7 SDM Aluminum Double XXL Pulley Mast Extension