Monument
Monument 1378Z Drain Testing Plug 100mm (4in) 1378Z
Model 1378Z
Best price
Lowest we’ve seenWhere to buy
| Retailer | Price | Availability | Visit |
|---|---|---|---|
| Cheapestchecked an hour ago | £11.53 | In stock | Visit Blueperry agriculture (UK) (opens in a new tab) |
 retailer's price from 16 Jul 2026 | £13.92 | In stock | Visit Blueperry Tool & Builders Merchants (UK) (opens in a new tab) |
 checked 2 hours ago | £14.95£17.47 | In stock | Visit Tooled Up (opens in a new tab) |
Prices exclude delivery. We may earn a commission if you buy through these links, which never affects the ranking above — it is always cheapest first.
Price history
Full price historyThis is the lowest price we have recorded. If you were waiting for a drop, this is it.
About this product
The Monument 1378Z is a 100mm (4in) drain testing plug designed for medium-sized drainage pipes, suited to commercial properties, multi-unit residential buildings and larger domestic installations. It bridges the gap between smaller household drains and larger commercial systems, making it a useful addition to a professional plumber's toolkit. Constructed from durable, flexible materials, the plug features removable top caps and rubber rings for easy maintenance. It is fitted using a simple wing nut mechanism which depresses the rubber cone, causing it to expand and create a watertight seal within the pipe. The plug is capable of sealing against pressures of up to 1.97 bar (29 psi), suitable for pressure testing drainage systems.
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