The Snowdrift Game. also known as the Hawk-Dove Game. is a social dilemma in which an individual can participate (cooperate) or not (defect) in producing a public good. It is relevant to a number of collective action problems in biology. https://www.roneverhart.com/Medline-Wheelchair-Arm-Trays-TRAY-ARM-WHEELCHAIR-ADJUSTABLE-LEFT-MDSR009636/