A transfer device for conveying a plurality of packaging units along a transfer path comprising: a first carrier having at least one first operative branch parallel to the transfer path; at least one first conveying element advanced along the first carrier; a second carrier adjacent to the first carrier and having at least one second operative branch parallel to the transfer path and to the first operative branch; and at least one second conveying element controlled independently from the first conveying element and advanced along the second carrier; wherein the first conveying element and the second conveying element are configured to retain therebetween a packaging unit of the plurality of packaging units and to advance the packaging unit along the transfer path.