Medical devices and methods for making and using medical devices are disclosed. An example medical device may include a guide extension catheter. The guide extension catheter may include a proximal member having a proximal end, a distal end, and a proximal diameter. The guide extension catheter may additionally include a collar member attached to an extension portion of the proximal member, where the extension portion may be located at the distal end of the proximal member. The extension portion may allow a delivery device to be inserted through the guide extension catheter to extend along a surface of the extension portion and align with a lumen of a distal sheath of the guide extension catheter.