what is a fluid head tripod

{"cid":"91200503","title":"Gopro Lightweight Fluid Head Tripod , 360 Degree Iphone Video Stabilizer Stick","imgUrl":"https:\/\/img.silkroadsl.com\/nimg\/f9\/2f\/88dd67c499a8cc2a9dff2840d0cf-200x200-1.jpg","attrs":{"Price":"negotiate","Brand Name":"ENZE","Place of Origin":"SHAOXING","Color":"Black","item":"iphone video stabilizer stick","keyword":"lightweight fluid head tripod","weight":"67g","Packaging Details":"Carton Box","Payment Terms":"L\/C, T\/T or negotiate"}}

{"cid":"91152229","title":"VCT-668 Pro Tripod with Damping Head Fluid Pan for SLR\/DSLR Canon Nikon +Carrying Bag","imgUrl":"https:\/\/img.silkroadsl.com\/nimg\/24\/46\/d3ec095f16e8e235cf43c4cbfa27-200x200-1.jpg","attrs":{"Price":"Negotiable","Brand Name":"Accept OEM","Model Number":"VCT-668","Minimum Order Quantity":"50PC","Delivery Time":"5-7days","Place of Origin":"China","Type":"Professional Tripod","Material":"Aluminum","Use":"Video Camera","Folded Length (mm)":"460","Extended Length (mm)":"1460","Weight (g)":"1300","Packaging Details":"10PC A CARTON","Payment Terms":"T\/T WESTERN UNION PAYPAL","Supply Ability":"1000PC per month"}}