According to the present invention there is provided an anvil assembly adapted for selective cooperation with a horn operatively connected to an ultrasonic wave generator such as to enable a textile workpiece disposed between the horn and the anvil assembly to be cut with the cut and simultaneously sealed. The anvil assembly comprises an anvil and a cradle, the anvil adapted to be selectively mounted onto the cradle in any one of at least two mounting positions, wherein corresponding to each mounting position the anvil comprises one peaked longitudinal cutting edge and a corresponding engagement section parallel to a longitudinal axis of the anvil. The corresponding positioning and engagement section is adapted for selective engagement for removably positioning and locked onto the cradle.