Double-Telescoping is the term used to define the type of lightsaber Kenner originally included with the action figure.
"The main part of the lightsaber slides out of the arm, as usual. However, the small tip further telescopes another inch from the main part of the lightsaber."
It is common for many people believe they have a Double Telescoping figure when in fact they have the standard, single-telescoping version.
Due to the high manufacturing cost of producing a 2-part lightsaber that required assembly, Kenner opted to mold a one-piece lightsaber that required no assembly.
A few early Darth Vader and Ben Kenobi figures have been produced with the "Double Telescoping" Lightsaber feature. They are extremely hard to find.
* Be aware of possible counterfeit figures.
According to rocketfettscollection.com, "it is one of only about 22 or fewer remaining in the world."
Produced in 1978 by Kenner
Original retail price: $2.49