diff --git a/copanier/models.py b/copanier/models.py
index 1b32c12..ceef0f1 100644
--- a/copanier/models.py
+++ b/copanier/models.py
@@ -44,7 +44,8 @@ class Base:
         for name, field_ in self.__dataclass_fields__.items():
             value = getattr(self, name)
             type_ = field_.type
-            if not isinstance(value, Base):  # Do not recast our classes.
+            # Do not recast our classes.
+            if not isinstance(value, Base) and value is not None:
                 try:
                     setattr(self, name, self.cast(type_, value))
                 except (TypeError, ValueError):
@@ -95,6 +96,7 @@ class Product(Base):
     description: str = ""
     url: str = ""
     img: str = ""
+    packing: int = None
 
     @property
     def label(self):
@@ -159,6 +161,10 @@ class Delivery(Base):
     def is_passed(self):
         return not self.is_foreseen
 
+    @property
+    def has_packing(self):
+        return any(p.packing for p in self.products)
+
     @classmethod
     def init_fs(cls):
         cls.get_root().mkdir(parents=True, exist_ok=True)
@@ -198,3 +204,10 @@ class Delivery(Base):
             if product.ref in order.products:
                 total += order.products[product.ref].wanted
         return total
+
+    def product_missing(self, product):
+        if not product.packing:
+            return 0
+        wanted = self.product_wanted(product)
+        orphan = wanted % product.packing
+        return product.packing - orphan if orphan else 0
diff --git a/copanier/static/app.css b/copanier/static/app.css
index 19c9731..087f87d 100644
--- a/copanier/static/app.css
+++ b/copanier/static/app.css
@@ -363,6 +363,10 @@ article.delivery {
 article.delivery th.person {
   max-width: 7rem;
 }
+td.missing,
+th.missing {
+  background-color: #db7734;
+}
 hr {
   background-color: #dbdbdb;
   border: none;
diff --git a/copanier/templates/delivery.html b/copanier/templates/delivery.html
index bde0e29..0133af1 100644
--- a/copanier/templates/delivery.html
+++ b/copanier/templates/delivery.html
@@ -10,6 +10,9 @@
                 <th class="ref">Référence</th>
                 <th class="product">Produit</th>
                 <th class="price">Prix</th>
+                {% if delivery.has_packing %}
+                    <th class="packing">Lot</th>
+                {% endif %}
                 <th class="amount">Total</th>
                 {% for email, order in delivery.orders.items() %}
                     <th class="person{% if delivery.is_passed and not order.paid %} not-paid{% endif %}">
@@ -26,7 +29,10 @@
                 <td class="ref">{{ product.ref }}</td>
                 <th class="product">{{ product.label }}</th>
                 <td>{{ product.price }} €</td>
-                <th>{{ delivery.product_wanted(product) }}</th>
+                {% if delivery.has_packing %}
+                    <td class="packing">{{ product.packing or '—'}}</td>
+                {% endif %}
+                <th{% if delivery.product_missing(product) %} class="missing" title="Les commandes individuelles ne correspondent pas aux lots"{% endif %}>{{ delivery.product_wanted(product) }}{% if delivery.product_missing(product) %} ({{ delivery.product_missing(product) }}){% endif %}</th>
                 {% for email, order in delivery.orders.items() %}
                     {% if product.ref in order.products %}
                     <td>{{ order.products[product.ref].wanted }}</td>
@@ -37,7 +43,10 @@
             </tr>
             {% endfor %}
             <tr><th class="total"><i class="icon-pricetags"></i> Total</th><td>—</td><td>—</td>
-                <td class="total">{{ delivery.total }} €</td>
+                {% if delivery.has_packing %}
+                    <td>—</td>
+                {% endif %}
+                <th class="total">{{ delivery.total }} €</th>
                 {% for email, order in delivery.orders.items() %}
                 <td>{{ order.total(delivery.products) }} €</td>
                 {% endfor %}
diff --git a/copanier/templates/edit_delivery.html b/copanier/templates/edit_delivery.html
index 456da85..cd3dd31 100644
--- a/copanier/templates/edit_delivery.html
+++ b/copanier/templates/edit_delivery.html
@@ -52,6 +52,8 @@
         <dd>Conditionnement d'une unité: 1kg, 33cl…</dd>
         <dt>description</dt>
         <dd>Plus de détails sur le produit.</dd>
+        <dt>packing</dt>
+        <dd>Contionnement final pour grouper les commandes, le cas échéant, en nombre d'unités.</dd>
         <dt>url</dt>
         <dd>Une URL éventuelle pointant sur une page présentant le produit.</dd>
         <dt>img</dt>
diff --git a/copanier/templates/place_order.html b/copanier/templates/place_order.html
index dd56c10..468445c 100644
--- a/copanier/templates/place_order.html
+++ b/copanier/templates/place_order.html
@@ -6,7 +6,7 @@
 {% include "includes/delivery_head.html" %}
 <form method="post">
     <table class="order">
-        <tr><th class="product">Produit</th><th class="price">Prix</th><th class="amount">Quantité</th></tr>
+        <tr><th class="product">Produit</th><th class="price">Prix</th><th class="packing">Lot</th><th class="amount">Quantité</th></tr>
         {% for product in delivery.products %}
         <tr>
             <th class="product">{{ product.label }}
@@ -16,7 +16,9 @@
                     {% endwith %}
                 {% endif %}</p>
             </th>
-            <td>{{ product.price }} €</td><td class="with-input"><input type="number" name="{{ product.ref }}" value="{{ order.get_quantity(product) }}"></td></tr>
+            <td>{{ product.price }} €</td>
+            <td{% if delivery.product_missing(product) %} class="missing" title="Les commandes individuelles ne correspondent pas aux lots"{% endif %}>{{ product.packing or "—" }}{% if delivery.product_missing(product) %} (manque {{ delivery.product_missing(product) }}){% endif %}</td>
+            <td class="with-input"><input type="number" name="{{ product.ref }}" value="{{ order.get_quantity(product) }}"></td></tr>
         {% endfor %}
     </table>
     <p>Total: {{ order.total(delivery.products) if order else 0 }} €</p>
diff --git a/tests/test_views.py b/tests/test_views.py
index 98e4aac..24a3ff2 100644
--- a/tests/test_views.py
+++ b/tests/test_views.py
@@ -101,6 +101,6 @@ async def test_export_products(client, delivery):
     resp = await client.get(f"/livraison/{delivery.id}/exporter/produits")
     wb = load_workbook(filename=BytesIO(resp.body))
     assert list(wb.active.values) == [
-        ("name", "ref", "price", "unit", "description", "url", "img"),
-        ("Lait", "123", 1.5, None, None, None, None),
+        ("name", "ref", "price", "unit", "description", "url", "img", "packing"),
+        ("Lait", "123", 1.5, None, None, None, None, None),
     ]