diff --git a/product.py b/product.py
index 53d94d2..53b6950 100644
--- a/product.py
+++ b/product.py
@@ -156,7 +156,7 @@ class Template(metaclass=PoolMeta):
 
     resolution_type = fields.Selection([('',""),
                                     ('analoga', "Analoga"),
-                                    ('digital', "Digital")], "Resolution Type", required=True,
+                                    ('digital', "Digital")], "Resolution Type",
                                    states={'required': Eval('calibration', False)},
                                    depends=['calibration'])
     d_resolution = fields.Float("Resolution d",