Maxs
From The DarkMod Wiki
The maxs spawnarg is used together with the mins spawnarg to define a collision model for entities when they do not have a CM in either the model file or a separate .cm file.
This spawnarg is only used when the spawnarg noclipmodel is set to zero.
Making a dedicated collision model should always be prefered over using this method.
See noclipmodel for further information and examples.