A system comprising a gas detector and a gas detector calibration cap for calibrating said gas detector , wherein the gas detector comprises: a gas detector housing, comprising: a front shell comprising one or more exhaust opening and a groove on an edge of the front shell ; and a back shell connected to the front shell comprising a first slot on a first side of the back shell , a second slot on a second side of the back shell ; and one or more sensors or filters disposed within the gas detector housing; and wherein the gas detector calibration cap comprises: a cap body , comprising a nozzle disposed on the cap body and an exhaust opening ; a first cap wing connected to the cap body , comprising a first opening and a first overhang extending through the first opening; a second cap wing connected to the cap body , comprising: a second opening; a second overhang extending through the second opening; and an extended strip attached to an end of the second cap wing , characterized in that the extended strip comprises a protrusion configured for opening the front shell of the gas detector by inserting said protrusion in said groove on the edge of the front shell of the gas detector and by applying force on said extended strip . wherein the gas detector comprises: a gas detector housing, comprising: a front shell comprising one or more exhaust opening and a groove on an edge of the front shell ; and a back shell connected to the front shell comprising a first slot on a first side of the back shell , a second slot on a second side of the back shell ; and one or more sensors or filters disposed within the gas detector housing; and a front shell comprising one or more exhaust opening and a groove on an edge of the front shell ; and a back shell connected to the front shell comprising a first slot on a first side of the back shell , a second slot on a second side of the back shell ; wherein the gas detector calibration cap comprises: a cap body , comprising a nozzle disposed on the cap body and an exhaust opening ; a first cap wing connected to the cap body , comprising a first opening and a first overhang extending through the first opening; a second cap wing connected to the cap body , comprising: a second opening; a second overhang extending through the second opening; and an extended strip attached to an end of the second cap wing , characterized in that the extended strip comprises a protrusion configured for opening the front shell of the gas detector by inserting said protrusion in said groove on the edge of the front shell of the gas detector and by applying force on said extended strip . a cap body , comprising a nozzle disposed on the cap body and an exhaust opening ; a first cap wing connected to the cap body , comprising a first opening and a first overhang extending through the first opening; a second cap wing connected to the cap body , comprising: a second opening; a second overhang extending through the second opening; and an extended strip attached to an end of the second cap wing , characterized in that the extended strip comprises a protrusion configured for opening the front shell of the gas detector by inserting said protrusion in said groove on the edge of the front shell of the gas detector and by applying force on said extended strip . a second opening; a second overhang extending through the second opening; and an extended strip attached to an end of the second cap wing , characterized in that the extended strip comprises a protrusion configured for opening the front shell of the gas detector by inserting said protrusion in said groove on the edge of the front shell of the gas detector and by applying force on said extended strip . <EOS>