Rubber Sheet

The Rubber Sheet, also known as Rubber Trampoline, will cause you to bounce when you fall on it. There must be a one block space underneath the sheet, and it needs to be connected to blocks on at least two sides for it to function. This has the effect of negating fall damage, as your bounces will gradually decrease in height until you come to a stop. If fallen on from heights over 11 blocks the sheet breaks.

Note
It should be noted that there is another form of Rubber Sheet which has not been fully implemented yet which is called ic2.blockHarz in game, but it is called "Sticky Sap Sheet" within the code. Originally this was placed by right-clicking with Sticky Resin and reduced fall damage if landed on. It must have any form of block underneath it to be placed but doesn't require any blocks around it, unlike the Rubber Sheet.