Cylindrical boot fixing portion of resin boot with annular exterior convex portion

A resin boot comprising a cylindrical boot fixing portion at an end thereof adapted to be fixed in position to a mating member by a boot band having a cylindrical inner surface,

• said boot fixing portion having an outer periphery on which the boot band is fitted, and an inner periphery fitted on an outer periphery of the mating member,
• said outer periphery of said boot fixing portion being provided with an annular convex portion disposed adjacent to an annular groove formed on the outer periphery of the mating member,
• wherein during a pre-tightening state, said annular convex portion projects radially outwardly from said outer periphery of said boot fixing portion, and said inner periphery of said boot fixing portion is substantially out of direct contact with the annular groove to define a pre-tightened annular groove cavity between said inner periphery of said boot fixing portion and the annular groove, and
• wherein during a tightening state, said inner periphery of said boot fixing portion is displaced radially inward by a tightening force of the boot band exerted on said annular convex portion to cause said inner periphery to firmly engage with the annular groove, said annular convex portion being displaced radially inwardly to conform with the cylindrical inner surface of the boot band.