▁and ▁geometry ▁less ons . ▁ ▁Man ufact urer ▁The ▁set ▁is ▁market ed ▁in ▁over ▁ 1 0 0 ▁countries ▁by ▁Hel ix , ▁a ▁company ▁based ▁in ▁St our bridge , ▁West ▁Mid lands . ▁ ▁Cont ents ▁It ▁consists ▁of ▁a ▁metal ▁tin ▁emb oss ed ▁on ▁the ▁front ▁with ▁a ▁drawing ▁of ▁Bal li ol ▁College ▁and ▁the ▁words ▁' THE ▁HE LI X ▁O X FOR D ▁SET ▁OF ▁M ATH EM AT IC AL ▁IN STR UM ENT S ▁CO MP LETE ▁& ▁A CC UR ATE ' ▁in ▁white ▁against ▁a ▁blue ▁background . ▁ ▁Inside ▁the ▁tin ▁there ▁are ▁two ▁set ▁squares , ▁a ▁ 1 8 0 ° ▁prot ractor , ▁a ▁ 1 5   cm ▁r uler , ▁a ▁metal ▁comp ass , ▁ ▁a ▁ 9   cm ▁p enc il , ▁a ▁p enc il ▁sharp ener , ▁an ▁er aser ▁and ▁a ▁ 1 0 mm ▁st enc il . ▁( In ▁the ▁ 1 9 7 0 s ▁a ▁st enc il ▁for ▁drawing ▁chemical ▁appar atus ▁was ▁included .) ▁There ▁is ▁also ▁a ▁fact ▁sheet ▁and ▁gl oss ary ▁of ▁mathematical ▁terms ▁with ▁a ▁school ▁tim et able ▁printed ▁on ▁the ▁back . ▁The ▁export ▁version ▁also ▁includes ▁div iders . ▁ ▁References ▁ ▁External ▁links ▁▁ ▁Mathemat ical ▁Inst ru ments ▁at ▁map ed hel ix . co . uk ▁ ▁Category : Dim ensional ▁instruments ▁Category : Math emat ics ▁education ▁in ▁the ▁United ▁Kingdom