---
product_id: 14093112
title: "304156 1 Gallon Duct Seal 321 Water Based Duct Sealant"
brand: "hardcast"
price: "¥27131"
currency: JPY
in_stock: true
reviews_count: 7
category: "Hardcast"
url: https://www.desertcart.jp/products/14093112-304156-1-gallon-duct-seal-321-water-based-duct-sealant
store_origin: JP
region: Japan
---

# 1 Gallon (128 fl oz) volume Noise-dampening sealant Silicone-based durability 304156 1 Gallon Duct Seal 321 Water Based Duct Sealant

**Brand:** hardcast
**Price:** ¥27131
**Availability:** ✅ In Stock

## Summary

> 🔧 Seal smart, sound silent, and stay ahead of the HVAC game!

## Quick Answers

- **What is this?** 304156 1 Gallon Duct Seal 321 Water Based Duct Sealant by hardcast
- **How much does it cost?** ¥27131 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.jp](https://www.desertcart.jp/products/14093112-304156-1-gallon-duct-seal-321-water-based-duct-sealant)

## Best For

- hardcast enthusiasts

## Why This Product

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

## Key Features

- • **Pest-Proof Your Ducts:** Effectively seals tiny gaps and sheet metal corners to keep unwanted critters out.
- • **Ultimate Sealant Power:** Silicone formula ensures long-lasting, flexible seals that resist cracking and shrinking.
- • **Generous 1-Gallon Capacity:** Bulk size designed for professional use, minimizing reorders and downtime.
- • **Noise-Cancelling Innovation:** Perfect for embedding noise-cancelling cloths to reduce HVAC operational sounds.
- • **Easy Application & Versatility:** Ideal for rubber and similar surfaces, making it a go-to for diverse HVAC sealing needs.

## Overview

Hardcast’s 304156 1 Gallon Duct Seal 321 is a professional-grade, silicone-based duct sealant designed for durable, flexible sealing of HVAC ductwork. With a large 128 fl oz volume, it excels at blocking air leaks, reducing noise by securing sound-absorbing materials, and preventing pest intrusion. Its compact, easy-to-apply formula is optimized for rubber and similar surfaces, making it an essential tool for managers and contractors aiming for efficient, quiet, and pest-free ventilation systems.

## Description

DS-321-GRAY-4-1 GAL

Review: Great product for sealing your ductwork! - This duct seal is fantastic! I use it to seal any penetrations, seal sheet metal corners to keep pests out of the tiny openings and most importantly I use it to glue in noise cancelling cloths inside the ductwork to reduce the sound of the metal moving when the evaporative cooler starts up.
Review: Cool - 👍

## Features

- DS-321-GRAY-4-1 GAL

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B00E0Q4Y6G |
| Batteries Included? | No |
| Batteries Required? | No |
| Best Sellers Rank | #272,570 in Tools & Home Improvement ( See Top 100 in Tools & Home Improvement ) #692 in Hardware Sealers |
| Brand | Hardcast |
| Color | gray |
| Customer Reviews | 4.6 4.6 out of 5 stars (18) |
| Date First Available | July 18, 2013 |
| Included Components | DS-321-GRAY-4-1 GAL |
| Is Discontinued By Manufacturer | No |
| Item Form | Liquid |
| Item Package Quantity | 1 |
| Item Weight | 10.56 pounds |
| Item model number | 304156 |
| Manufacturer | Hardcast |
| Material | Silicone |
| Number of Items | 1 |
| Package Dimensions | 8.11 x 7.76 x 7.52 inches |
| Part Number | 304156 |
| Style | Compact |
| Surface Recommendation | Rubber or similar surfaces |
| UPC | 063853280050 |
| Unit Count | 128.0 Fluid Ounces |
| Water Resistance Level | Not Water Resistant |

## Product Details

- **Brand:** Hardcast
- **Item Weight:** 4.8 Kilograms
- **Material:** Silicone
- **Style:** Compact
- **Water Resistance Level:** Not Water Resistant

## Images

![304156 1 Gallon Duct Seal 321 Water Based Duct Sealant - Image 1](https://m.media-amazon.com/images/I/31EaMwdWSXL.jpg)

## Customer Reviews

### ⭐⭐⭐⭐⭐ Great product for sealing your ductwork!
*by A***C on February 1, 2026*

This duct seal is fantastic! I use it to seal any penetrations, seal sheet metal corners to keep pests out of the tiny openings and most importantly I use it to glue in noise cancelling cloths inside the ductwork to reduce the sound of the metal moving when the evaporative cooler starts up.

### ⭐⭐⭐⭐ Cool
*by S***F on September 1, 2025*

👍

### ⭐⭐⭐⭐⭐ Best stuff
*by J***N on July 23, 2025*

Works perfectly

## Frequently Bought Together

- Hardcast 304156 1 Gallon Duct Seal 321 Water Based Duct Sealant
- Rolled Mastic Duct Sealants Foils 3'' X100

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**Shop now:** [https://www.desertcart.jp/products/14093112-304156-1-gallon-duct-seal-321-water-based-duct-sealant](https://www.desertcart.jp/products/14093112-304156-1-gallon-duct-seal-321-water-based-duct-sealant)

---

*Product available on Desertcart Japan*
*Store origin: JP*
*Last updated: 2026-03-20*