Each of the adjusting straps has a loop around it made of elastic material. Nylon is chosen for its strength and elastic stretch properties. The skin can be either thin and elastic or thicker. Knee wraps are made of varying combinations of cotton and elastic. Tendons are viscoelastic structures, which means they exhibit both elastic and viscous behaviour. Furthermore, momentum is conserved in both elastic and inelastic scattering. Use of good quality elastic make fitted sheets durable. The folds are made up of elastic and fatty tissue. This is distinct from elastic deformation, which is reversible. However, the difference between elastic and inelastic collision was not understood at the time. Flexure bearings rely on elastic properties of material. Fibronectin also acts as a skeleton for the elastic tissue formation. Linear deformations of elastic materials can be approximated as adiabatic. The macula flava is composed of fibroblasts, ground substances, elastic and collagenous fibers. Surface tension is responsible for approximately 2/3 of the inward elastic recoil forces.