dˈʊɹɹɪŋ mˌænjuːfˈæktʃɚ, ɐ lˈɛŋθ ʌv bˌoːɹəsˈɪlᵻkˌeɪt ɡlˈæs tˈuːb wˌɪtʃ hɐz hæd ðɪ ɪnsˈaɪd sˈɜːfɪs kˈoʊɾᵻd wɪð ɐ fˈɑːsfɚkəntˈeɪnɪŋ kˈɑːmpaʊnd ɪz fˈɪld wɪððə ɹˌeɪdɪoʊˈæktɪv tɹˈaɪɾiəm.
During manufacture, a length of borosilicate glass tube which has had the inside surface coated with a phosphor-containing compound is filled with the radioactive tritium.