A foldable treadmill is provided that can be easily reoriented for variable exercise inclinations, as well as, for convenient storage. The present invention permits an attendant, for example a nurse, to press a single button to bring the back rest to a lowered back rest position without having to keep the button pressed so that the attendant is free to immediately begin administering emergency procedures while the back rest is lowering. The side plates are capable of being flexed away from each other for allowing the HDD to be placed therebetween. Another aspect provides a composition comprising an engineered corpus cavernosum tissue comprising SVF cells and corpus cavernosum cells, wherein the SVF cells can be mixed with or encasing the corpus cavernosum cells, and methods of uses thereof, for example in method for the treatment of impotence and erectile dysfunction andor enhance or construct a penis. The outer symbol has a larger size than the inner symbol, and is opaque. Light-emitting devices whose power consumption is reduced by including such light-emitting elements are also provided.