This is a vacuum actuated piston. it works by being connected to a vacuum pump and when an object blocks the air flowing into the piston it is retracted by the vacuum pulling itself and the object upwards. in some use cases it may need a spring added between the housing and the piston for it to descend properly when object is removed if your vacuum is too strong. it can work with noc rubber suction cup on the end but for best results buy sucker feet or print your own from tpu. i am using mine on an industrial paper folder to improve its paper feeding capabilities but the possibilities are endless. this item is still being changed and improved files will be made better eventually. feel free to improve them yourself and send me what you have done!