This is a Double piston extender and yes that is a link sooooo yaaa u might want to watch it 🙂 or u might like to read this 1 min tutorial on how to do it you will need .8 redstone, .2 sticky piston, 4. repeaters and a button or lever. It works better with a lever the first thing u want to do is put down 2 sticky piston in a line on the first piston put down a repeater and click it 3 times put 4 redston on the back on the next piston put 3 repeaters in a line and click all of them once. Later, put redstone 1 piece on the back and put a block in the front of the piston and run redstone in to the block. and you done!