a removable cap assembly having a cap with a curved side wall having an inner surface and an outer surface . a top portion extends from the side wall . a boss extends perpendicularly from the top portion in the shape of an inverted trapezoid , where the boss has a bottom and a top . a first circumferential rib extends perpendicularly from the top of the boss . a stopper is dimensioned to seal the opening , having an inverted trapezoidal shape complementary to the boss . the stopper is maintained in the cap by the inverted trapezoid shape of said boss . the stopper includes a disc shaped base , a cylindrical wall portion extending from the base , a first groove in the base surrounding the wall portion dimensioned to receive the bottom of the boss . an appliance member is adapted to be positioned within the hole and extending through the opening .