Yes, Mr Beam has a manual focus which must be adjusted according to the height of the material. The laser beam has a very steep angle, meaning the laser result doesn't variate a lot by +/-5mm. 38mm is the maximum object height which can be cut or engraved by Mr Beam.
Every Mr Beam comes with a focus tool, which helps to measure the distance between the material and the laser head very easily.
In the following article you will find more information on focusing the laser head.