Cycleops Riser Block
The CycleOps Riser Block offers a stable, worry free ride in any rear mounted trainer, with a three level design that will allow you to choose the level of difficulty that you require.
If you stack two CycleOp Riser Blocks, you can simulate climbing in your workout, and stacking two blocks equals 12 different adjustment levels.
700.CO9701 - Cycleops Riser Block