The SwordSlasher Adjustable Harpoon© (Patent Pending) is a must have in any serious offshore fishermen's arsenal while in pursuit of big game fish.  The harpoon is made from airplane grade anodized aluminum tubing.  The outer tube is oblong in shape which makes it very comfortable to hold and handle.  The outer tube also has a channel running down the inside of its entire length that functions as a channel guide for the inner tube to track on while extending.  This feature keeps the inner tube from spinning while being extended, which takes the guess work out of finding the next locking position.  There is also a hand grip and an end cap grip on the outer tube.  The back end cap grip has a 2 ½ inch stainless steel cable loop coming out of it.  This loop is secured to an aluminum pin that goes across the diameter of the outer tube and is bonded in place.  This loop's function is to provide a place to secure a safety line.
The harpoon lengths:

Completely closed without the shaft screwed in place:6 feet

Completely closed with the shaft screwed in place:7 feet 7 inches

Position 1:8 feet 3 inches

Position 2:9 feet 4 inches

Position 3:10 feet 5 inches

Position 4:11 feet 6 inches

Position 5:12 feet 7 ¼ inches

The harpoon costs $215.00 plus S.H. (Florida residents add the appropriate sales tax) fully rigged.  There is a stainless steel inter changeable 3 ½ inch gap gaff head available for an additional $25.00. 

This Product has been filed and has patent pending status.
The inner tube has a locking pin that secures and locks the tube in one of the 5 locking holes predrilled at set length on the outer tube.  To extend or shorten the pole you simply push the locking pin in with your finger and extend or retract the pole to the desired length.  There is also a pin on its underside that rides inside the channel located on the inside of the outer pole, again this feature keeps the inner tube from spinning while extending or retracting the inner pole.
The inner pole has a stainless steel insert bonded inside the far end.  This insert gives the harpoon extra weight for water and fish penetration.  The insert has a threaded hole in its center.  This hole provides a spot for the 20 inch 3/8 inch stainless steel threaded harpoon shaft to screw into.
A bronze harpoon dart sits on the far end of the harpoon shaft.  The dart has 5 feet of coated 3/8" stainless steel cable crimped to it.  There is 30 feet of rope attached to the cable.  The rope is used to secure the harpoon dart head to a cleat and used to control and lead the fish to the boat after it has been darted.