diff --git a/dashcam-transfer.py b/dashcam-transfer.py
index ceb54dd..3fcde30 100644
--- a/dashcam-transfer.py
+++ b/dashcam-transfer.py
@@ -1,19 +1,21 @@
 #!/usr/bin/env python3
 """Transfer dashcam MP4 files from SD card to USB-SSD with date/camera structure."""
 
+import argparse
 import fcntl
 import logging
 import os
 import re
 import shutil
+import subprocess
 import sys
 
 SD_CARD = "/mnt/sdcard"
 SOURCE_DIR = os.path.join(SD_CARD, "Novatek", "Movie")
 SSD = "/mnt/ultratouch"
 TARGET_BASE = os.path.join(SSD, "dashcam")
-LOG_FILE = "/var/log/dashcam-transfer.log"
-LOCK_FILE = "/var/run/dashcam-transfer.lock"
+LOG_FILE = "/tmp/dashcam-transfer.log"
+LOCK_FILE = "/tmp/dashcam-transfer.lock"
 
 CAMERA_MAP = {"F": "front", "B": "back"}
 FILE_PATTERN = re.compile(r"^(\d{8})\d{6}_\d+([FB])\.MP4$")
@@ -101,7 +103,17 @@ def ensure_free_space(needed_bytes, target_base):
     logging.info("Ruimte vrijgemaakt: %d bytes door %d mappen", freed, len(removed))
 
 
+def parse_args():
+    parser = argparse.ArgumentParser(description="Dashcam transfer tool")
+    parser.add_argument(
+        "--limit", "-n", type=int, default=0,
+        help="Maximum aantal bestanden om over te zetten (0 = alle)"
+    )
+    return parser.parse_args()
+
+
 def main():
+    args = parse_args()
     setup_logging()
     lock_fd = acquire_lock()
 
@@ -113,6 +125,9 @@ def main():
         logging.info("Geen MP4 bestanden gevonden in %s", SOURCE_DIR)
         return
 
+    if args.limit > 0:
+        files = files[:args.limit]
+
     total_size = sum(
         os.path.getsize(os.path.join(SOURCE_DIR, fname)) for fname, _, _ in files
     )
@@ -129,18 +144,50 @@ def main():
         os.makedirs(target_dir, exist_ok=True)
         src = os.path.join(SOURCE_DIR, fname)
         dst = os.path.join(target_dir, fname)
+
+        if os.path.exists(dst):
+            src_size = os.path.getsize(src)
+            dst_size = os.path.getsize(dst)
+            if src_size == dst_size:
+                logging.info(
+                    "Bestaat al en klopt: %s → %s/%s/", fname, date_str, CAMERA_MAP[cam]
+                )
+                os.remove(src)
+                ok += 1
+                continue
+            else:
+                logging.warning(
+                    "Doel %s bestaat maar is anders (%d vs %d bytes) — overschrijf",
+                    dst, dst_size, src_size,
+                )
+                os.remove(dst)
+
         try:
-            shutil.move(src, dst)
-            logging.info(
-                "Verplaatst: %s → %s/%s/", fname, date_str, CAMERA_MAP[cam]
+            subprocess.run(
+                ["cp", src, dst], check=True, capture_output=True, timeout=600
             )
-            ok += 1
-        except OSError as e:
-            logging.error("Fout bij verplaatsen %s: %s", fname, e)
+        except (subprocess.CalledProcessError, OSError) as e:
+            logging.error("Fout bij kopiëren %s: %s", fname, e)
             errors += 1
+            continue
+
+        dst_size = os.path.getsize(dst)
+        src_size = os.path.getsize(src)
+        if dst_size != src_size:
+            logging.error(
+                "Verificatie mislukt %s: %d vs %d bytes", fname, src_size, dst_size
+            )
+            errors += 1
+            continue
+
+        os.remove(src)
+        logging.info(
+            "Overgezet: %s → %s/%s/ (%d bytes)", fname, date_str, CAMERA_MAP[cam], src_size
+        )
+        ok += 1
 
     logging.info(
-        "Transfer voltooid: %d ok, %d fouten, %d bytes", ok, errors, total_size
+        "Transfer voltooid: %d ok, %d fouten", ok, errors
     )