A silver-colored metal window lock mechanism designed for use with UPVC windows.
Technical drawing of a metal strip with two mounting holes spaced 43mm apart, showing dimensions including 8mm thickness, 16mm width, and a customizable length and backset (20mm or 22mm).
Diagram showing two types of UPVC window gearboxes: Offset Gearbox on the left and Inline Gearbox on the right, with red window profiles and labeled parts for comparison.
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A silver-colored metal window lock mechanism designed for use with UPVC windows.Technical drawing of a metal strip with two mounting holes spaced 43mm apart, showing dimensions including 8mm thickness, 16mm width, and a customizable length and backset (20mm or 22mm).Diagram showing two types of UPVC window gearboxes: Offset Gearbox on the left and Inline Gearbox on the right, with red window profiles and labeled parts for comparison.

UPVC Window Lock - Inline Espag - 400mm – Replacement uPVC Window Part

AvocetSKU: HS1989
162 reviews from verified buyers
Price:
£7.49

Key benefits

  • Inline espag mechanism - modern flush-fit window locking
  • 250mm to 800mm lengths - match your window height
  • Universal direct replacement - fits most uPVC casement windows

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Description

This is the mechanism inside the window frame that is operated by the handle

Gearbox is positioned centrally on the rail (inline)

Important Measurements

1) Overall length

2) The 'Backset' (20mm, 22mm)

4) Rail Width (Usually 16mm)

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Frequently Asked Questions

A 400mm inline espag window lock is a multipoint locking mechanism used in uPVC windows. It secures the window by engaging locking points along the frame when the handle is operated.

The 400mm measurement refers to the overall length of the espag mechanism. It’s essential to match this size with your existing lock to ensure a correct replacement and proper function.

Common signs include difficulty turning the handle, the window not locking properly, or the mechanism feeling loose or worn. Replacing the espag can restore both security and smooth operation.

No, compatibility depends on window size, backset, and spindle dimensions. Always check your current mechanism’s specifications before purchasing a replacement.

If your window is hard to open or close, doesn’t lock securely, or makes unusual noises, it may be time for a replacement. To learn more, read: Top Signs Your Window Mechanism Needs Replacing (And What to Buy)