This vario clamp is predominantely made of aluminium and is thus extremly robust. It is designed do fit on round uprights or speed bars. (It is also a good fit on most rubber backed aerofoil section uprights used on hang gliders.) It will also fit other tube sizes from about 25mm up to about 70mm diameter.
I actually find it fits adequately well on all aluminum aerofoil sections too and find it a good compromise if flying more than one glider.
The clamp is based on an extruded aluminium 'U' section with two rubber inserts which give good grip against tubes of various diameters.
The clamp is generally positioned on the upright (though some use on the speed bar) and attached firmly with two elasticated Velcro strips. The stalk part ot the clamp sticks forward from the upright to position the insturment in front of the upright. The angle and direction of this part of the clamp can be altered with a thumb screw and a ball joint giving many mounting angles and positions.
The instrument is attached with an M4 male screw turned by a thumb screw. Many insturments, such as varios or flight computers, have the female M4 thread as a mount. The attachment plate also features a large rubber 'O' ring which helps to grip the instrument and stop it rotating once you have set your instrument at the desired angle.
The M4 screw mounting system is used on many flight instruments and all Brauniger and Flytec instruments.
A great product.