Click the Tolerancing button on the Dimensions window for these options:

The dimension tolerance is the positive and negative values showing the amount of variation allowed from the standard measurement.

None: Allows no tolerance for the dimension,meaning that it must be exact.

The second option allows you to set one value that will be used as the positive and negative dimension tolerance.

The third option allows you to set separate values for the positive dimension tolerance and the negative dimension tolerance.

Same As (hand icon): Click to copy the properties of an existing dimension.