"I obtained this thermos for free" Seems correctly usual to me. "That thermos was for free" Seems undesirable: I might just say "That thermos was free." herisson Aunque no encuentro nada en el DRAE ni en el DPD on line, me animo a afirmar que las comillas y el apóstrofo https://hectordwoev.bcbloggers.com/37322751/free-grimelda-fun-house-play-things-to-know-before-you-buy