Are long solid objects, with restraints on either end, used to keep a submissive stretched out, in a set position.
These 'sex toys' are basically long tubes designed to keep limbs apart, as well as to prevent the subject from moving, or if they do, to create a painful reaction.
Most common are 'leg stretchers' that are simply bars or round tubes, that hold the legs a set distance apart.
The cuffs that are attached, prevent the submissive from moving their legs further apart, the bar prevents them from closing them.
Ball stretchers are different.
These are usually placed above the balls, horizontally around the scrotum, which in turn forces the balls down into the stretched skin of the sac.