Pistons are blocks which can push and pull blocks by the use of a redstone.
More Pistons Mod
The More Pistons Mod adds five new types of pistons to Minecraft Pocket Edition. All pistons can be toggled by the use of a redstone signal and each of them can push and pull a unique length of blocks. As of version 0.13 redstone exists in Minecraft but so far we haven’t got any pistons. If you are tired of waiting for an official update of the game then give this mod a try – it works very well and even adds in a couple of new pistons never (officially) seen in any Minecraft version before!
Piston Mod
Pistons are blocks which can push and pull blocks by the use of a redstone. According to one of the developers of Minecraft Pocket Edition it’s expected to be an official feature in the next version of the game (0.14.0). But if you can’t wait and want access to pistons right now then you can use this mod. The mod is more limited but it does provide a taste of what’s to come.