diff --git a/product_usability/models/__init__.py b/product_usability/models/__init__.py
index 7ef8d55..ee1a5d5 100644
--- a/product_usability/models/__init__.py
+++ b/product_usability/models/__init__.py
@@ -1,4 +1,7 @@
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
 
 from . import product
+from . import product_template
+from . import product_supplierinfo
+from . import product_price_history
 from . import pricelist
diff --git a/product_usability/models/product.py b/product_usability/models/product.py
index 5a95211..c502ec4 100644
--- a/product_usability/models/product.py
+++ b/product_usability/models/product.py
@@ -1,41 +1,31 @@
-
+# © 2015-2016 Akretion (http://www.akretion.com)
+# @author Alexis de Lattre <alexis.delattre@akretion.com>
+# @author Raphaël Valyi <rvalyi@akretion.com>
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
 
 from odoo import models, fields
 
 
-class ProductTemplate(models.Model):
-    _inherit = 'product.template'
-
-    name = fields.Char(track_visibility='onchange')
-    type = fields.Selection(track_visibility='onchange')
-    categ_id = fields.Many2one(track_visibility='onchange')
-    list_price = fields.Float(track_visibility='onchange')
-    sale_ok = fields.Boolean(track_visibility='onchange')
-    purchase_ok = fields.Boolean(track_visibility='onchange')
-    active = fields.Boolean(track_visibility='onchange')
-
-    def show_product_price_history(self):
-        self.ensure_one()
-        products = self.env['product.product'].search(
-            [('product_tmpl_id', '=', self._context['active_id'])])
-        action = self.env['ir.actions.act_window'].for_xml_id(
-            'product_usability', 'product_price_history_action')
-        action.update({
-            'domain': "[('product_id', 'in', %s)]" % products.ids,
-        })
-        return action
-
-
 class ProductProduct(models.Model):
     _inherit = 'product.product'
 
-    default_code = fields.Char(track_visibility='onchange', copy=False)
-    barcode = fields.Char(track_visibility='onchange', copy=False)
-    weight = fields.Float(track_visibility='onchange')
-    active = fields.Boolean(track_visibility='onchange')
+    default_code = fields.Char(
+        track_visibility='onchange',
+        copy=False)
+
+    barcode = fields.Char(
+        track_visibility='onchange',
+        copy=False)
+
+    weight = fields.Float(
+        track_visibility='onchange')
+
+    active = fields.Boolean(
+        track_visibility='onchange')
+
     price_history_ids = fields.One2many(
-        'product.price.history', 'product_id',
+        comodel_name='product.price.history',
+        inverse_name='product_id',
         string='Product Price History')
 
     _sql_constraints = [(
@@ -50,24 +40,9 @@ class ProductProduct(models.Model):
 
     def show_product_price_history(self):
         self.ensure_one()
-        action = self.env['ir.actions.act_window'].for_xml_id(
+        action = self.env.ref(['ir.actions.act_window'].for_xml_id(
             'product_usability', 'product_price_history_action')
         action.update({
             'domain': "[('product_id', '=', %d)]" % self.ids[0],
         })
         return action
-
-
-class ProductSupplierinfo(models.Model):
-    _inherit = 'product.supplierinfo'
-
-    name = fields.Many2one(
-        domain=[('supplier', '=', True), ('parent_id', '=', False)])
-
-
-class ProductPriceHistory(models.Model):
-    _inherit = 'product.price.history'
-
-    company_currency_id = fields.Many2one(
-        related='company_id.currency_id', readonly=True, compute_sudo=True,
-        string='Company Currency')
diff --git a/product_usability/models/product_price_history.py b/product_usability/models/product_price_history.py
new file mode 100644
index 0000000..af7b390
--- /dev/null
+++ b/product_usability/models/product_price_history.py
@@ -0,0 +1,16 @@
+# © 2015-2016 Akretion (http://www.akretion.com)
+# @author Alexis de Lattre <alexis.delattre@akretion.com>
+# @author Raphaël Valyi <rvalyi@akretion.com>
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
+
+from odoo import models, fields
+
+
+class ProductPriceHistory(models.Model):
+    _inherit = 'product.price.history'
+
+    company_currency_id = fields.Many2one(
+        related='company_id.currency_id',
+        readonly=True,
+        compute_sudo=True,
+        string='Company Currency')
diff --git a/product_usability/models/product_supplierinfo.py b/product_usability/models/product_supplierinfo.py
new file mode 100644
index 0000000..2526eab
--- /dev/null
+++ b/product_usability/models/product_supplierinfo.py
@@ -0,0 +1,13 @@
+# © 2015-2016 Akretion (http://www.akretion.com)
+# @author Alexis de Lattre <alexis.delattre@akretion.com>
+# @author Raphaël Valyi <rvalyi@akretion.com>
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
+
+from odoo import models, fields
+
+
+class ProductSupplierinfo(models.Model):
+    _inherit = 'product.supplierinfo'
+
+    name = fields.Many2one(
+        domain=[('supplier', '=', True), ('parent_id', '=', False)])
diff --git a/product_usability/models/product_template.py b/product_usability/models/product_template.py
new file mode 100644
index 0000000..1e7344e
--- /dev/null
+++ b/product_usability/models/product_template.py
@@ -0,0 +1,42 @@
+# © 2015-2016 Akretion (http://www.akretion.com)
+# @author Alexis de Lattre <alexis.delattre@akretion.com>
+# @author Raphaël Valyi <rvalyi@akretion.com>
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
+
+from odoo import models, fields
+
+
+class ProductTemplate(models.Model):
+    _inherit = 'product.template'
+
+    name = fields.Char(
+        track_visibility='onchange')
+
+    type = fields.Selection(
+        track_visibility='onchange')
+
+    categ_id = fields.Many2one(
+        track_visibility='onchange')
+
+    list_price = fields.Float(
+        track_visibility='onchange')
+
+    sale_ok = fields.Boolean(
+        track_visibility='onchange')
+
+    purchase_ok = fields.Boolean(
+        track_visibility='onchange')
+        
+    active = fields.Boolean(
+        track_visibility='onchange')
+
+    def show_product_price_history(self):
+        self.ensure_one()
+        products = self.env['product.product'].search(
+            [('product_tmpl_id', '=', self._context['active_id'])])
+        action = self.env['ir.actions.act_window'].for_xml_id(
+            'product_usability', 'product_price_history_action')
+        action.update({
+            'domain': "[('product_id', 'in', %s)]" % products.ids,
+        })
+        return action