Lukas
General Explanation
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5 is also the default value if you don’t specify one. Note that a high value for the intensity most likely puts more additional material on the design to reduce the support of the part.
Build direction
the The build direction is z by default. If you want to use another direction than that you have to rotate the part. The only exception to this are symmetrical Designs, for them the build direction is the positive z direction if the symmetry coordinate system.
More practical information are provided in this hands on tutorial: Support Reduction - Gripper