diff --git a/equipment.py b/equipment.py
index ea79838..5692a75 100644
--- a/equipment.py
+++ b/equipment.py
@@ -8,6 +8,9 @@ from trytond.i18n import gettext
 #from .exceptions import NotSequenceEquipment
 from trytond.exceptions import UserError
 
+
+_MAINTENANCE_FREQUENCY = [(6, 'Seis Meses'),
+                          (12, 'Doce Meses')]
 class OpticalEquipment(Workflow, ModelSQL, ModelView):
     'Optical Equipment'
     __name__ = 'optical_equipment.equipment'
@@ -26,7 +29,7 @@ class OpticalEquipment(Workflow, ModelSQL, ModelView):
     company = fields.Many2One('company.company', "Company", readonly=True)
     location = fields.Many2One('stock.location', "Location",
                                states={'readonly': Eval('state') != 'draft',},)
-    propietary = fields.Many2One('party.party', "Propietary",
+    propietary = fields.Many2One('party.party',"Propietary",'party',
                                  states={'readonly': Eval('state') != 'draft',},)
     propietary_address = fields.Many2One('party.address', "Propietary Address", required=True,
                                          domain=[('party', '=', Eval('propietary'))],
@@ -79,6 +82,8 @@ class OpticalEquipment(Workflow, ModelSQL, ModelView):
     software_version = fields.Char("Software version", size=None,
                                    states={'readonly': Eval('state') != 'draft',},)
 
+    maintenance_frequency = fields.Selection(_MAINTENANCE_FREQUENCY, "Maintenance Frequency",
+                                             depends=['propietary'])
 
     @classmethod
     def __setup__(cls):
@@ -119,6 +124,14 @@ class OpticalEquipment(Workflow, ModelSQL, ModelView):
     def default_company():
         return Transaction().context.get('company')
 
+    
+    @fields.depends('propietary', 'maintenance_frequency')
+    def on_change_propietary(self):
+        if self.propietary.client_type == 'ips':
+            self.maintenance_frequency = 'Sies Meses'
+        else:
+            self.maintenance_frequency = 'Doce Meses'
+    
     @fields.depends('product', 'equipment_type','use',
                     'biomedical_class', 'calibration',
                     'mark_category', 'model_category')
diff --git a/view/optical_equipment_form.xml b/view/optical_equipment_form.xml
index fc82100..7dcf5e8 100644
--- a/view/optical_equipment_form.xml
+++ b/view/optical_equipment_form.xml
@@ -37,6 +37,8 @@
     <field name="useful_life"/>
     <label name="warranty"/>
     <field name="warranty"/>
+    <label name="maintenance_frequency"/>
+    <field name="maintenance_frequency"/>
     <label name="serial"/>
     <field name="serial"/>
     <label name="health_register"/>