Wireless Door and Window Sensors: MCT-43, MCOC-43 and Wi-Fi Models Explained

Short answer: wireless door and window sensors come in three kinds. 433 MHz alarm sensors such as the MCT-43 (₹650), MCJ-43 (₹749) and MCOC-43 (₹899) have no siren of their own and only work with an alarm panel. A Wi-Fi sensor, the MC-TY (₹1,249), connects straight to your router and sends a push notification to the Tuya app, with no hub. A self-alarm sensor, the MC-AL (from ₹299), simply sounds a loud alarm of its own when the door opens. Pick by what you already have: a panel, Wi-Fi, or nothing.

Door and window contacts are the most common sensor in any alarm, because every break-in starts with something opening. They are also the item buyers most often get wrong: a 433 MHz contact bought for a home with no panel does nothing on its own. This guide explains the difference, compares our models on what their listings state, and shows where to fit them.

How does a door or window sensor work?

Each sensor has two parts: a body with a magnetic switch inside, and a small magnet. One part goes on the frame and the other on the door or window, lined up next to each other. While the door is shut, the magnet holds the switch in one state. When the door opens and the magnet moves away, the switch changes and the body sends a radio signal (or sounds its own alarm). The MCJ-43 listing gives a detection distance of 25 to 35 mm and asks for a gap of no more than 1 cm between the parts when you fit them.

Which 433 MHz sensor works with my alarm panel: MCT-43, MCJ-43 or MCOC-43?

All three are 433 MHz contacts for wireless alarm panels. None of them can work alone. The differences are range, pairing and price.

Model	What the listing states	Pairing	Price
MCT-43	433 MHz, built-in omnidirectional antenna, flashes to warn of a low battery, peel-and-stick fitting; made for GSM alarm panels	On the alarm panel	₹650
MCJ-43	433 MHz, 1527 encoding, 80 m or more in open space, 3V button cell, for doors, windows, drawers and cabinets	On the alarm panel	₹749
MCOC-43	433 MHz only, about 120 m from the panel in open space, battery and stickers included	On the alarm panel only, not through the app	₹899
ACJ-1008 door sensor	433/868 MHz, 200 m in open area, CR123A battery; made only for the ACJ-1008 panel	On the ACJ-1008	₹2,200

For most flats on an ACJ-400, 405 or 407 panel, the MCT-43 is the default: it is the cheapest and is listed for GSM alarm panels. Choose the MCOC-43 for a door or window far from the panel, such as a terrace door two floors up, because its listing gives the longest range of the three. Choose the MCJ-43 if you also want to protect a drawer or cabinet. A 433 MHz label alone does not guarantee a match, so WhatsApp us your panel model before ordering and we will confirm. If your site uses the ACJ-1008, use only its own sensor; our ACJ-1008 guide explains why.

What does a Wi-Fi door sensor do differently?

The MC-TY joins your 2.4 GHz Wi-Fi directly and talks to the Tuya app, so it needs no panel or hub. When the door opens while you are out, it pushes a notification to your phone. You can share it with family members, see a history of openings and get a low-battery alert. It runs on 2 LR03 (AAA) batteries and works with Alexa. It suits a single door you want to keep an eye on, such as a main door, a store room or a parent's room, but it depends on your Wi-Fi and internet being up. If you also want a loud siren at the door, Combo-CN118 (₹3,950) pairs the MC-TY with a siren, 2 remotes and a 12V supply.

When is a simple self-alarm sensor enough?

The MC-AL sounds its own alarm as soon as the door or window opens; the 8-piece set's listing rates it at 105 dB. There is no app, no panel and no phone alert; you switch it on at night and off in the morning. It is useful to know when a child opens the main door, to hear a balcony door at night, or as a low-cost deterrent in a small shop. The 8-piece listing gives about a year of battery life on 3 button cells if the door opens once a day.

Pack	Price	Per sensor
MC-AL single	₹299	₹299
MC-AL set of 4	₹969	about ₹242
MC-AL set of 8	₹1,600	₹200

How to fit a door or window sensor

1. Body on the frame, magnet on the door. The MCJ-43 listing asks for the battery part on the frame and the magnet part on the door or window, so the body does not swing.
2. Fit on the opening side. Mount near the top corner opposite the hinges, where the door moves the most as it opens.
3. Line them up. Keep the alignment marks level and the gap small; within 1 cm for the MCJ-43.
4. Use screws where you can. Tape is fine to start, but heat and dust in Indian summers loosen adhesive. Screws keep the alignment.
5. Sliding windows: put the body on the fixed frame and the magnet on the sliding sash, at the edge that moves.
6. Test every one. Arm the panel, open each door and window, and check that the right zone name shows on the panel or app.

Which openings need a sensor?

Start with every outside door, then every window a person can reach from the ground, a terrace, a balcony or a staircase. Bathroom ventilators and small fixed windows can usually be left to a motion sensor inside. Our PIR motion sensor guide covers how one PIR can back up several windows in a room. For a full budget, the alarm system price guide works out a 2BHK, and the Security System Builder lets you count openings room by room.

Wiring a new building instead? The MC-3T wired NO/NC door sensor costs ₹350, and a pack of 10 MC-2T wired contacts costs ₹1,799. See every model in wireless door and window sensors.

FAQ

Can a wireless door sensor work without an alarm panel?

The MCT-43, MCJ-43 and MCOC-43 cannot; they have no siren and need a panel. The MC-TY works alone over Wi-Fi with app alerts, and the MC-AL works alone with its own built-in alarm.

Which door sensor works with the ACJ-400?

The MCT-43 is a 433 MHz contact made for GSM alarm panels and is the usual add-on for ACJ-400 homes. Send us your panel model on WhatsApp and we will confirm before you order.

How far can a wireless door sensor be from the alarm panel?

The MCOC-43 listing gives about 120 m and the MCJ-43 80 m or more, both in open space. Walls and floors cut this down, so test the signal before final fitting.

Do I need a sensor on every window?

Fit one on every window a person can reach. For windows that cannot be opened or are too small to climb through, a PIR motion sensor in the room is usually enough.

How do I know when the battery is low?

The MCT-43 flashes its light when the battery is low, and the MC-TY sends a low-battery alert to the Tuya app.

Can I pair the MCOC-43 from my phone app?

No. Its listing says it pairs on the alarm panel only, not through the app.

Prices are NavKar Systems website prices on 27 October 2026, inclusive of GST, and may change.