A cartridge-housing system comprising an assay cartridge (31, 100) for use in a molecular diagnostics assay and a support housing (51, 90) for holding the assay cartridge (31, 100); the assay cartridge (31, 100) comprising: an assay region; a first end comprising a first engagement member (35, 101) for engaging with the support housing (51, 90); and a second end comprising a second engagement member (36, 102) for engaging with the support housing (51, 90); wherein the second engagement member (36, 102) comprises a clip (36, 102), the clip (36, 102) being formed by a resilient element extending from the second end of the cartridge and a fastening element extending from said resilient element; wherein the clip comprises a release element extending from the resilient element actuatable to release the clip (36, 102) from a support housing (51, 90) in use, wherein the first engagement member (35, 101) comprises a lip (35, 101), the lip being formed by a protrusion extending upwardly from the upper surface of the first end of the cartridge (31, 100); wherein the support housing (51, 90) comprises: a first cooperating member (55, 91) configured to engage with the lip (35, 101); and a second cooperating member (56, 57, 93, 94) configured to engage with the clip (36, 102); wherein the support housing (51, 90) comprises a channel (52, 92) for receiving the cartridge (31, 100); wherein the first cooperating member (55, 91) is provided at one end of the channel (52, 92) and the second cooperating member (56, 57, 93, 94) is provided at the other end of the channel (52, 92), wherein the first cooperating member (55, 91) comprises a first recess for receiving the lip (35, 101) of the cartridge (31, 100), wherein the second cooperating member (56, 57, 93, 94) comprises an abutment element (56, 94) and a second recess (57, 93). an assay region; a first end comprising a first engagement member (35, 101) for engaging with the support housing (51, 90); and a second end comprising a second engagement member (36, 102) for engaging with the support housing (51, 90); wherein the second engagement member (36, 102) comprises a clip (36, 102), the clip (36, 102) being formed by a resilient element extending from the second end of the cartridge and a fastening element extending from said resilient element; wherein the clip comprises a release element extending from the resilient element actuatable to release the clip (36, 102) from a support housing (51, 90) in use, wherein the first engagement member (35, 101) comprises a lip (35, 101), the lip being formed by a protrusion extending upwardly from the upper surface of the first end of the cartridge (31, 100); wherein the support housing (51, 90) comprises: a first cooperating member (55, 91) configured to engage with the lip (35, 101); and a second cooperating member (56, 57, 93, 94) configured to engage with the clip (36, 102); wherein the support housing (51, 90) comprises a channel (52, 92) for receiving the cartridge (31, 100); wherein the first cooperating member (55, 91) is provided at one end of the channel (52, 92) and the second cooperating member (56, 57, 93, 94) is provided at the other end of the channel (52, 92), wherein the first cooperating member (55, 91) comprises a first recess for receiving the lip (35, 101) of the cartridge (31, 100), wherein the second cooperating member (56, 57, 93, 94) comprises an abutment element (56, 94) and a second recess (57, 93). a first cooperating member (55, 91) configured to engage with the lip (35, 101); and a second cooperating member (56, 57, 93, 94) configured to engage with the clip (36, 102); wherein the support housing (51, 90) comprises a channel (52, 92) for receiving the cartridge (31, 100); wherein the first cooperating member (55, 91) is provided at one end of the channel (52, 92) and the second cooperating member (56, 57, 93, 94) is provided at the other end of the channel (52, 92), wherein the first cooperating member (55, 91) comprises a first recess for receiving the lip (35, 101) of the cartridge (31, 100), wherein the second cooperating member (56, 57, 93, 94) comprises an abutment element (56, 94) and a second recess (57, 93).