The TR-55 debuted in 1955 but there was a model that was manufactured earlier called the TR-52. The TR-52 was troubled by the fact that the case ended up deforming. As shown in the photo, the design featured a black base covered with a white grill frame but the entire white frame rose up from the black base and deformed. Polystyrene was used as the material but the product was not released to the market because of the joining together of two materials with different expansion coefficients and it became the "phantom" No. 1 unit. Plastic material research at the time was still in a domain of unfamiliarity and due to what happened, the company started to engage in plastic molding technology and material research in a full-fledged way.