the longitudinal axis l the inner body 3 has then a front face 31 arranged substantially parallel to the front face 21 of the outer body 2 and spaced apart therefrom by means of one or more spacing elements 6 preferably the spacing element 6 or each spacing element is manufactured in one piece or however made integral to the outer body 2 the inner body 3 has then a rear face 32 closing the device 1 on the rear side in the herein considered preferred embodiment the faces 21 31 and 32 have substantially circular geometry the inner body 3 at its own side skirt 30 bears an annular recess 310 defined in particular by a substantially cylindrical bottom wall 311 and by two side walls resulting plain in the side or longitudinal view of fig1 and 3 the device 1 comprises then connection means 4 which in the present example are obtained integrally to the side skirt 20 of the outer body 2 in particular in the present example the connection means 4 comprises a coupling sleeve designated too with 4 with substantially cylindrical geometry and arranged according to an axis t substantially orthogonal to the longitudinal axis l the sleeve 4 bears an inner wall with section decreasing along the axis t and in particular decreasing towards the side skirt 20 of the outer body 2 in the present example such decreasing section is obtained by means of a stepped.