塞克斯 transliterates Western surnames Sykes / Sachs / Saxe / Sax. Pattern:
塞 ('Sy-/Sa-') +
克 ('-ke') +
斯 ('-s'). Note: the unrelated English noun 'sex' is rendered
性 in Chinese, never this transliteration.
塞 here is read sài; the same character also reads sāi ('to stuff') and sè (a literary 'to block') - this transliteration uses sài.