Abstract: An attachment device for inserting and removing the spike for obtaining fluids from a medical fluid bag such as an IV bag or a bag for peritoneal dialysis comprises a base holding the spike positioned to be inserted into the neck of the bag, and opposed toggles pivoting on the base which engage the neck of the bag during insertion and push the neck onto the spike. During removal of the spike the toggles operate an engagement which contacts the end of the neck and pushes the spike out of the neck of the bag. The device has a hand operable slide which affects the motions of the toggles and the toggles have dependent legs ending in the engagement. The attachment device is designed to protect the end of the spike and to prevent contamination.