Channel that opens in response to stretch forces in the membrane lipid bilayer. Forms a nonselective ion channel with a conductance of about 3 nanosiemens. May participate in the regulation of osmotic pressure changes within the cell. Homopentamer (By similarity). Can form a homotetramer (in vitro), but this may not be physiologically relevant (PubMed:19701184). Belongs to the MscL family.