Items, Held items, #896
Terrain Extender flings for 60 power, a Held items item since Generation VII
PokéAPI item 896 of 2,223, Held items category, Items pocket
Effect, in PokéAPI's words
Terrain Extender: “Held: Extends the holder’s Terrain effects to 8 turns.”
Held: When the holder changes the Terrain (whether by move or ability), it will last 8 turns instead of 5.
Games
Terrain Extender is listed in the text of 4 version groups, first in Generation VII
Game index by generation
IIIIIIIVVVIVIIVIIIIX
Named in
Sun and MoonUltra Sun and Ultra MoonLet's Go Pikachu and Let's Go EeveeSword and Shield