This is a cylinder stroke stop set light duty. They are different sizes and can be used individually or in combination stacked. They are used to limit cylinder strokes or often used with heavy weight loads/weight boxes etc on 3 point hitches to take the constant load of the cylinder and seals and make a mechanical stop for the load instead of stressing the system. You put them around the piston rod, then float the load onto the stops lightly , then take lever out of "float" and leave. These are not designed to operate the cylinder often, made to be resting stops mainly. If you are going to constantly use the cylinder, then you should look for expensive lined stroke limiters. These are inexpensive import stops that do the job if used correctly.