Improved transfer set

A transfer assembly split transferring fluid from a first container (22) having an open end sealed with a pierceable closure (30) to a second container, said transfer set (220, 320) comprising: a tubular housing member (236 , 336) having a proximal end adapted to be attached to said first open end of the container and an open distal end; a united cap (242, 342) so as releasably to said distal open end of said tubular housing member (236, 336) sealing said open distal end; and a piercing member (240, 340) telescopically supported in said tubular housing member and having an end proximal bore (262) adapted to pierce said closure of said first container and a distal end, wherein the distal end (264 , 364) of said piercing member (240, 340) is fixedly releasable to said cover, supporting said lid, and retaining releasably, said piercing member (240, 340) during the assembly of the transfer said container and prior to removal of said cap.