This is a block that makes itself Solid or Invisible depending if the ON/OFF Switch is ON or OFF, making it perfect for Puzzle levels (Uses ExAnimation). The .zip incluides: .asm for the ON and the OFF variation of the block, ExGFX of the block and a .txt that has a Tutorial to make the blocks work. The graphics are re-created from a video made by the channel "Fortaleza Reznor".
Rejected because a General Switch Block pack does exist, indeed. You can find it here, by MarioE. To achieve the effect you intended to, use switch_act.asm, then use $14AF as the RAM (the block instructs you to do so) and the inverted flag.