Product Measurements: 1.4″ x 0.4″ x 0.3″ with 15.5″ long chain. Weighs just 0.4 ounces. Instructions To Open & Close Pendant: The Housing has a hinged opening mechanism. To open simply hold the necklace by the chain and place the tool pick on the slot next to the chain ring. Delicately pull and it will open into a V shape. Place your tracker inside and close back the housing by pressing until you hear a soft clicking sound. Now you are ready to enjoy your new accessory for your fitness activity tracker.