Beginning in 1990, the "Generation" or "G" series ushered in a new platform for the cleaner. The addition of TechDrive variable power assist eliminated 90% of the effort required to move the unit back and forth. The current model, the Kirby Avalir 2™ continues the tradition that converts the vacuum into several different units beginning with the Model 508 in 1948. With the introduction of the 1945 Model 505, the handle could be removed and the machine converted to a portable unit with a shoulder strap so that cleaning in difficult areas could be performed, and the machine converted into a canister-type cleaner with a long hose attached to the front for dusting tasks. With most vacuum cleaner models, the rubber drive belt that powers the brush bar, an integral component with most modern machines, remains in place and is only examined when it breaks. Vacuum attachments are available on other machines but don't require the drive belt to be disconnected and the carpet nozzle with the rotating brush bar removed. Kirby attachments are connected to the power unit in place of the carpet nozzle, and disconnecting the drive belt is involved in the process that adds to its flexibility.