diff --git a/disco.py b/disco.py
index 71f1fcc..849c5c4 100644
--- a/disco.py
+++ b/disco.py
@@ -80,13 +80,15 @@ def extract_products_from_har(har_path: str) -> list[dict]:
 
 
 def rootsv_to_sku(rootsv: str) -> str:
-    """Convert rootSV like '0419363_1' to SKU like '41936301'."""
+    """Convert rootSV like '0419363_1' to SKU like '41936301'.
+
+    The rootSV base (minus leading zero) + '01' gives the DG item number.
+    The '_N' suffix is a variant/image index, not part of the SKU.
+    """
     if not rootsv:
         return ""
-    parts = rootsv.split("_")
-    base = parts[0].lstrip("0")
-    suffix = parts[1] if len(parts) > 1 else ""
-    return base + suffix
+    base = rootsv.split("_")[0].lstrip("0")
+    return base + "01"
 
 
 def build_product_url(upc: str) -> str: