These super tiny Pentalobe screws are slightly different than the ones we found in the iPhone 5 and 5s.

¡ʍouʞ oʇ ǝʌol plnoʍ ǝʍ 'sı uoıʇɐuıɯouǝp ǝɥʇ ʇɐɥʍ ʍouʞ ɹǝpun-uʍop spuǝıɹɟ ɹno ɟo ʎuɐ ɟı pu∀

EDIT: it's a 50 cent coin roughly an inch in diameter for the yanks.