---
product_id: 13391490
title: "Master Lock 378DAT Trailer Coupler Lock, 2-5/16-Inch"
brand: "master lock"
price: "3432886₫"
currency: VND
in_stock: true
reviews_count: 13
category: "Master Lock"
url: https://www.desertcart.vn/products/13391490-master-lock-378dat-trailer-coupler-lock-2-5-16-inch
store_origin: VN
region: Vietnam
---

# Fits 1-7/8 to 2-5/16 in. couplers Advanced pick & pry resistant lock Rust & corrosion-proof alloy steel Master Lock 378DAT Trailer Coupler Lock, 2-5/16-Inch

**Brand:** master lock
**Price:** 3432886₫
**Availability:** ✅ In Stock

## Summary

> 🔐 Lock in your trailer’s safety, unlock your peace of mind.

## Quick Answers

- **What is this?** Master Lock 378DAT Trailer Coupler Lock, 2-5/16-Inch by master lock
- **How much does it cost?** 3432886₫ with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.vn](https://www.desertcart.vn/products/13391490-master-lock-378dat-trailer-coupler-lock-2-5-16-inch)

## Best For

- master lock enthusiasts

## Why This Product

- Trusted master lock brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Universal Fit:** Designed to fit most straight tongue couplers from 1-7/8 in. up to 2-5/16 in., covering top brands.
- • **Unmatched Security:** Advanced locking mechanism resists picking and prying for ultimate trailer protection.
- • **All-Weather Durability:** Powder-coated alloy steel finish ensures rust and corrosion resistance season after season.
- • **Effortless Installation:** Simple, no-fuss setup means you’re locked and loaded in seconds—no tools required.
- • **Trusted Brand Assurance:** Backed by Master Lock’s lifetime guarantee, giving you peace of mind on every haul.

## Overview

The Master Lock 378DAT Trailer Coupler Lock is a robust, corrosion-resistant security solution designed for straight tongue trailer couplers ranging from 1-7/8 to 2-5/16 inches. Featuring an advanced locking mechanism that resists picking and prying, it offers superior protection and easy installation. Trusted by professionals and backed by a lifetime guarantee, this lock ensures your trailer stays secure wherever the road takes you.

## Description

The Master Lock 378DAT features a 2-5/16 in. (59 mm) trailer coupler lock, designed to resist rust and corrosion. The advanced locking mechanism provides resistance to picking and prying. Fits most couplers 1-7/8 in. (48 mm), 2 in. (51 mm) and 2-5/16 in. (59 mm) from brands such as Reese®, Fulton®, Valley®, Atwood®, Shelby®, Putnam®, Hammerblow, Dutton Lainson®, UFP. The Lifetime Guarantee provides peace of mind from a brand you know and can trust.

Review: A better way ! , High Quality, Easy install. - Very happy with this product. This is a more modern version of some of the other ones that I was looking at. I tried the style that slides on like a gorilla style lock that has a little pin that pops up. Those wiggle and you can get them off. This design is simple yet , I feel very effective. Super easy install. It definitely is a better way. Highly recommend. Note : I have a 2 5/16 ball. This model is designed for the 2 5/16 ball. 378 Model. Fits perfect.
Review: Good quality unit - Have tried other types of locks on my trailer that were either hard to install or left the ball socket exposed which makes it vulnerable to someone being able to modify a ball to fit around the normal latch. This lock covers the hole completely and the plunger contacts above the flange of the tongue so the lock can't be easily removed.

## Features

- Coupler lock is best used for trailers; Works best with Straight Tongue Trailer Couplers
- Advance locking mechanism resists picking and prying
- Designed to resist rust and corrosion
- Fits most couplers 1-7/8 in. (48 mm), 2 in. (51 mm) and 2-5/16 in. (59 mm); Does not fit Gooseneck Trailer Couplers
- Includes one trailer coupler lock, two keys

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B0002YPD7O |
| Automotive Fit Type | Universal Fit |
| Best Sellers Rank | #103,536 in Automotive ( See Top 100 in Automotive ) #179 in Towing Hitch Locks |
| Brand | Master Lock |
| Customer Reviews | 4.3 4.3 out of 5 stars (949) |
| Date First Available | September 14, 2004 |
| Exterior | Machined |
| Finish Type | Powder Coated |
| Global Trade Identification Number | 00071649213236 |
| Is Discontinued By Manufacturer | No |
| Item Weight | 3.4 pounds |
| Item model number | 378DAT |
| Manufacturer | Master Lock |
| Manufacturer Part Number | 378DAT |
| Material | Alloy Steel |
| Model | 378DAT |
| OEM Part Number | 378DAT |
| Product Dimensions | 7.25 x 5.5 x 3.5 inches |
| Special Features | Fits most 2-5/16 in. Couplers |
| UPC | 071649213236 |
| Vehicle Service Type | Trailer |

## Product Details

- **Brand:** Master Lock
- **Finish Type:** Powder Coated
- **Item Weight:** 3.4 Pounds
- **Material:** Alloy Steel
- **Vehicle Service Type:** Trailer

## Images

![Master Lock 378DAT Trailer Coupler Lock, 2-5/16-Inch - Image 1](https://m.media-amazon.com/images/I/81BbqVfNDBL.jpg)
![Master Lock 378DAT Trailer Coupler Lock, 2-5/16-Inch - Image 2](https://m.media-amazon.com/images/I/616ZvFWHwEL.jpg)
![Master Lock 378DAT Trailer Coupler Lock, 2-5/16-Inch - Image 3](https://m.media-amazon.com/images/I/51dHdVVrj9S.jpg)
![Master Lock 378DAT Trailer Coupler Lock, 2-5/16-Inch - Image 4](https://m.media-amazon.com/images/I/81PRWNC-eRL.jpg)

## Available Options

This product comes in different **Style** options.

## Customer Reviews

### ⭐⭐⭐⭐⭐ A better way ! , High Quality, Easy install.
*by R***T on February 10, 2021*

Very happy with this product. This is a more modern version of some of the other ones that I was looking at. I tried the style that slides on like a gorilla style lock that has a little pin that pops up. Those wiggle and you can get them off. This design is simple yet , I feel very effective. Super easy install. It definitely is a better way. Highly recommend. Note : I have a 2 5/16 ball. This model is designed for the 2 5/16 ball. 378 Model. Fits perfect.

### ⭐⭐⭐⭐⭐ Good quality unit
*by I***I on October 5, 2025*

Have tried other types of locks on my trailer that were either hard to install or left the ball socket exposed which makes it vulnerable to someone being able to modify a ball to fit around the normal latch. This lock covers the hole completely and the plunger contacts above the flange of the tongue so the lock can't be easily removed.

### ⭐⭐⭐⭐⭐ Good Deterrent
*by A***R on June 20, 2024*

I like the exact ball fit on this lock instead of a universal hitch lock because I also lock the hitch closed on the lock for added security. Universal hitch locks have a smaller ball that will fall out of a larger connector if someone is successful at breaking the lock. Any lock can be broken by a determined thief, but hopefully this will be enough of a Deterrent, or make enough noise to attract attention.

## Frequently Bought Together

- Master Lock Trailer Lock, Trailer Coupler Lock, Fits 2-5/16 in. Couplers, 378DAT, Silver
- Master Lock Trailer Hitch Lock, Fits 1-7/8 in., 2 in., and Most 2-5/16 in. Trailer Couplers, Weather Resistant Automotive Hitch Lock with Keys, 377KA

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*Product available on Desertcart Vietnam*
*Store origin: VN*
*Last updated: 2026-02-21*