These Butterfly Fasteners from Moroso are self ejecting with a spring loaded release which also holds the pin captive once released so it can't fall out. The thumb screw handle requires only a 1/4 turn to release and negated the need for any tools to fasten or unfasten which is perfect for when fast removal is requiredSpring loaded self ejecting mechanismPin is retained to the base when released to prevent it falling outThumb screw handle for operation with no toolsRobust steel constructionSizes:5-6mm (0.198-0.233") grip length: 8mm (0.312") diameter pin, 12.7mm (0.500") pin length.8.8-9.7mm (0.348-0.383") grip length:  8mm (0.312") diameter pin, 16.5mm (0.650") pin length.Sold in packs of 10 with attachment springs.