You can use ‘Remove Doubles’ from the specials menu (w key). After clicking it you can find in the left panel (the one you get pressing t key) the merge distance option which works as threshold
“Remove Doubles” is the name in Blender. It’s in the [W] menu. You can set the distance at which vertices will be merged in the tools panel on the left ([T] key) or press [F6] which will bring a popup for the parameters.