Tesla is a slim, male Arrancar with blonde hair. He has an odd turquoise marking on his right cheek and wears an eyepatch over his right eye, either because he is missing it or because he simply wears one to show his admiration and respect for Nnoitra. During the time when Nnoitra was still the 8th Espada, he is seen without the eyepatch and he has his right eye.

Tesla also wears a different style jacket from most Arrancar in that it resembles a lab coat, with the sleeves rolled up to his elbows and what appears to be medals sewn across his chest. He also wears black gloves and boots. The remains of his Hollow mask appear to be a thin upper jaw which forms a circlet around his forehead. When Nnoitra was the 8th Espada, his hair was noticeably longer.


Source: Bleach Wiki