Temerian gauntlets are light armor gauntlets in The Witcher 3: Wild Hunt and are part of the Temerian Armor set free DLC. They can only be purchased from Bram in White Orchard.
Whether due to a bug or intentionally, the upgraded New Game + version can be purchased in a regular game as well. At level 29, it will replace the level 4 version in Bram's inventory. Similarly, it cannot be purchased before reaching level 29 even in a New Game +.