Abstract: The invention relates to an insert for connecting a flexible tube to a shower head which has an axial pipe (13) and, externally, has keying (17) and sealed truing (15, 16) structure in a seat of said shower head. It has one elastic tab (19) with a tooth (20) able to clip into a hole (21') formed at the same level of said seat. The keying structure (17) prevents the rotation of the insert while the tooth prevents an axial unscrewing.