|This article is about a/an changer in Juken Sentai Gekiranger.|
- "Boil! Power of the Beasts! Beast On!"
- ―Transformation call[src]
Beast-Fist Transformation GekiChanger (獣拳変身ゲキチェンジャー Jūken Henshin GekiChenjā) were two-piece transformation devices worn over the forearms as gloved arm-guards. They were developed by SCRTC to maximize the wearer's Geki then harness that amplified geki as a power source to catalyze the Gekiranger transformation. Aside from their primary function, GekiChangers have a store function which can store a number of tools, including weapons, inside a pocket dimension that can be accessed via the gloves' three buttons. The traditional routine for transformation among GekiRanger involves their trademark Wushu hand postures along with the transformation cry of "Boil! Power of the Beasts! Beast On!" (たぎれ！獣の力！ビースト・オン！ Tagire! Kemono no chikara! Bīsuto On!), though simply "Beast On!" (ビースト・オン！ Bīsuto On!) suffices.
At the climax of the Legend War, the GekiChangers were made redundant when the Gekirangers sacrificed their powers with the rest of the first 34 Super Sentai to destroy the invasion force of the Space Empire Zangyack. Resurfacing as Ranger Keys, the Gekiranger powers would be used by the Gokaigers to assume their forms via the Gokai Change. Ultimately, the Gokaigers returned their borrowed powers to their rightful owners after overthrowing Zangyack.