The National Institute of Standards and Technology provides guidance for American users of SI to write the plural as henries. People do not capitalize unit names.
ð ə WORD_BOUNDARY n æ ʃ ə n ə l WORD_BOUNDARY ɪ n s t ɪ t uː t WORD_BOUNDARY ʌ v WORD_BOUNDARY s t æ n d ə ɹ d z WORD_BOUNDARY æ n d WORD_BOUNDARY t ɛ k n ɑ l ə d̠ʒ i WORD_BOUNDARY p ɹ ə v aɪ d z WORD_BOUNDARY ɡ aɪ d ə n s WORD_BOUNDARY f ɔ ɹ WORD_BOUNDARY ʌ m ɛ ɹ ɪ k ə n WORD_BOUNDARY j uː z ə ɹ z WORD_BOUNDARY ʌ v WORD_BOUNDARY s iː WORD_BOUNDARY t ə WORD_BOUNDARY ɹ aɪ t WORD_BOUNDARY ð ə WORD_BOUNDARY p l ʊ ɹ ɹ ə l WORD_BOUNDARY æ z WORD_BOUNDARY h ɛ n ɹ i z WORD_BOUNDARY p iː p ə l WORD_BOUNDARY d uː n ɑ t WORD_BOUNDARY k æ p ɪ t ə l aɪ z WORD_BOUNDARY j uː n ɪ t WORD_BOUNDARY n eɪ m z WORD_BOUNDARY