An insole for footwear, characterised in that it comprises, in combination: - a first body having an upper surface comprising a first groove defining a first channel (C1), extending close to at least part of an edge of said upper surface , and at least a second groove defining a second channel (C2), extending between a central zone of said upper surface and an edge of the upper surface ; - a second body having a first lower surface , in contact with the upper surface of the first body for closing said first and second channel (C1, C2), and a second upper surface , said second body comprising at least a first through opening , positioned, in use, at least at part of the first channel (C1), and at least a second through opening , positioned, in use, at least at part of the at least a second channel (C2); - an attachment , connected to said first body and second body , in turn comprising: at least a first conduit (D1), in fluid communication with the first channel (C1) and with the outside environment, and at least a second conduit (D2), in fluid communication with the at least a second channel (C2) and with the outside environment, wherein: - the at least a first conduit (D1) comprises two conduits, an inlet conduit and an outlet conduit , configured for the circulation in the first channel (C1) of fluid to and from the outside environment; - the attachment comprises a lower portion , having a plurality of grooves defining the at least a first conduit (D1) and the at least a second conduit (D2), and an upper portion , configured for covering said at least a first and at least a second conduit (D1, D2); - and the attachment has a main axis of extension and wherein the attachment extends along said main axis of extension for a length of between 1 cm and 40 cm. - a first body having an upper surface comprising a first groove defining a first channel (C1), extending close to at least part of an edge of said upper surface , and at least a second groove defining a second channel (C2), extending between a central zone of said upper surface and an edge of the upper surface ; - a second body having a first lower surface , in contact with the upper surface of the first body for closing said first and second channel (C1, C2), and a second upper surface , said second body comprising at least a first through opening , positioned, in use, at least at part of the first channel (C1), and at least a second through opening , positioned, in use, at least at part of the at least a second channel (C2); - an attachment , connected to said first body and second body , in turn comprising: at least a first conduit (D1), in fluid communication with the first channel (C1) and with the outside environment, and at least a second conduit (D2), in fluid communication with the at least a second channel (C2) and with the outside environment, - the at least a first conduit (D1) comprises two conduits, an inlet conduit and an outlet conduit , configured for the circulation in the first channel (C1) of fluid to and from the outside environment; - the attachment comprises a lower portion , having a plurality of grooves defining the at least a first conduit (D1) and the at least a second conduit (D2), and an upper portion , configured for covering said at least a first and at least a second conduit (D1, D2); - and the attachment has a main axis of extension and wherein the attachment extends along said main axis of extension for a length of between 1 cm and 40 cm. <EOS>