The head on your DG H4 tripod is secured by a screw and you should be able to remove the head with simple tools. However, these screws were often expoxied in place so you may have to use a solvent such as acetone and/or put the tripod in a vise and apply considerable force with a long-handled wrench. Once you remove the old head a Davis & Sanford ball head--we recommend the BHQ11-- can easily be installed. Please let us know how you make out, or if you have any further questions. Best regards, Jason Schneider
