ɐ sˈɛkənd klˈæs ʌv dˈaɪvɚz æɾ ˌɪntɚmˈiːdiət dˈɛpθs ʌvwˈɪtʃ duːnˌɑːt ɹᵻkwˈaɪɚ tɹˈaɪmɪks sˈʌmtaɪmz kˈæɹi ɐ pˈoʊni bˈɑːɾəl fɔːɹ ɪmˈɜːdʒənsiz, ˌæzˌɪz tˈɔːt ɪn mˈɛni dˈiːp dˈaɪvɪŋ kˈoːɹsᵻz.
A second class of divers at intermediate depths of  which do not require trimix sometimes carry a pony bottle for emergencies, as is taught in many deep diving courses.