Sash for closing an architectural opening, comprising: i) weight-bearing frame , placed towards the inside, preferably in wood; ii) at least one transparent element , preferably of a planar shape, suitable to allow the passage of light through the sash , housed on, and supported by, the weight-bearing frame ; iii) a cover frame , placed towards the outside, preferably in aluminium, fitted on the weight-bearing frame , suitable to protect the latter on the outer side; wherein the cover frame comprises: n) a structure comprising upright elements and transversal elements suitable to engage each other perpendicularly, wherein which the upright element identifies, along its extension, an upright cavity and/or an upright groove (410") and the transversal element identifies, along its extension, a transversal cavity ; m) a plurality of locking elements , each locking element is made in one piece and comprises: - an upright portion comprising a locking lip suitable to be housed, with a transverse insertion, in the upright groove (410"); characterised in that each locking element further comprises: - a transversal portion suitable to be snap-engaged, with a rotation of the locking element , in the transversal cavity of the transversal element ; and wherein the upright portion and transversal portion are mutually interacting in such a way that the snap-engagement between the transversal portion and transversal element reached by the rotation of the locking element , transmits an action to the locking lip that engages the walls of the upright groove (410") wherein is housed and that forcibly locks the upright element to the transversal element . i) weight-bearing frame , placed towards the inside, preferably in wood; ii) at least one transparent element , preferably of a planar shape, suitable to allow the passage of light through the sash , housed on, and supported by, the weight-bearing frame ; iii) a cover frame , placed towards the outside, preferably in aluminium, fitted on the weight-bearing frame , suitable to protect the latter on the outer side; n) a structure comprising upright elements and transversal elements suitable to engage each other perpendicularly, wherein which the upright element identifies, along its extension, an upright cavity and/or an upright groove (410") and the transversal element identifies, along its extension, a transversal cavity ; m) a plurality of locking elements , each locking element is made in one piece and comprises: - an upright portion comprising a locking lip suitable to be housed, with a transverse insertion, in the upright groove (410"); characterised in that each locking element further comprises: - a transversal portion suitable to be snap-engaged, with a rotation of the locking element , in the transversal cavity of the transversal element ; and - an upright portion comprising a locking lip suitable to be housed, with a transverse insertion, in the upright groove (410"); characterised in that each locking element further comprises: - a transversal portion suitable to be snap-engaged, with a rotation of the locking element , in the transversal cavity of the transversal element ; and - a transversal portion suitable to be snap-engaged, with a rotation of the locking element , in the transversal cavity of the transversal element ; and <EOS>