Abstract: A golf tee (1) for use preferably on a mat comprise a base (4) providing locking (4a, 4b) and pivotal elements in the mat. The locking and pivotal elements may be provided by an inverted T-shaped base (4) that easily may be inserted into a slit (57) in the mat and there after the tee may be turned so as to slide the protruding legs (4a, 4b) of the inverted T-shaped base (4) in under the mat structure and thus locking and pivotal elements are provided. An adapter (60, 80) for mounting of the golf tee in mats with a hole instead of a slit is provided and an adapter for mounting in grass is also provided wherein the adapter is arranged to be pressed into place from above.