A drainable bag for an ostomy bag, the bag including an attachment mechanism for attachment to inter alia a peristomal pad, the attachment mechanism comprising first 4 and second 16 attachment members associated with the bag and pad respectively. Each attachment member has a locating surface 8, 10. The first and second attachment members are shaped to allow one attachment member to be located on and secured to the other attachment member in such a way as to allow only rotational movement of the attachment members in respect of each other when the locating surfaces are not engaged, whereby the rotational movement is prevented by engagement of the locating surfaces of the first and second attachment members. Initial linking of attachment members 4 and 16 allows rotation with respect to one another however renewal of release liners on surfaces 32, 34 and adhesive contact therebetween fixes the orientation of pad and bag.