Depending on the model of reptile radiator you have and its' required settings, your reptile might be in slight danger of getting burnt should they come into contact with the element itself.
While unlikely providing you are using a reliable and purpose built reptile radiator, most like to stay on the side of caution and buy a Swell Reptile Radiator Guard.
Made from safe and durable materials, each Reptile Radiator guard is long lasting, and is built to fit popular models such as the Habistat Reptile Radiator, maintaining a safe distance between the hot elements in the radiator and your reptile's skin/scales, negating the risk of burns.
Dimensions - 14" x 10" x 2" (36cm x 25.5cm x5cm)
NOTE: this is the GUARD ONLY.