Cheap And Discounts MD-211R Wireless Mini Door Window Detector Magnetic Switch for Focus 433MHz/868MHz Alarm System ST-VGT ST-IIIB ST-IV ST-III Wholesale. Buy Directly From Merchant Witzone Electronics Co., Ltd. Enjoy ✓Free Shipping Worldwide! ✓90 Days Buyer Protection. ✓Easy Return. ✓Money Back Guarantee.