A gold-colored metal window mechanism component, possibly made of brass or another alloy, with a visible screw and mounting bracket.
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 25mm).
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.
A gold-colored metal window mechanism component, possibly made of brass or another alloy, with a visible screw and mounting bracket.
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 25mm).
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.
Avocet

UPVC Window Lock - Offset Espag - 250mm – Replacement uPVC Window PartUPVC Window Lock - Offset Espag - 250mm

£6.99 SKU: HS2662
Backset
Backset
Order by 2pm for same-day dispatch
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Same-day dispatch on orders before 2pm

This is the mechanism inside the window frame that is operated by the handle Gearbox is positioned over to one side on the rail (offset) Important Measurements

1) Overall length

2) The 'Backset' (20mm, 25mm)

4) Rail Width (Usually 16mm)

Key benefits
  • Offse espag mechanism - fits older offset-pattern windows
  • 250mm to 800mm lengthst - match your window height
  • Direct replacement - fits most older uPVC windows
Product overview

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

Gearbox is positioned over to one side on the rail (offset)

Important Measurements

1) Overall length

2) The 'Backset' (20mm, 25mm)

4) Rail Width (Usually 16mm)
Delivery & Returns

How much is delivery?

UK Mainland Delivery is £2.99 on all items no matter how many you order!

Northern Ireland, Scottish Highlands, Channel Islands £6.00.

We do not offer International Delivery (Ireland, France, Spain etc).

When will my order be dispatched?

Orders before 3pm (Monday to Friday) are usually dispatched same day but may take up to 24 hours.

When will I receive my item?

We ship on 2 working day courier. Fully Tracked. Tracking will be emailed on dispatch. 

Special order items such as keyed alike locks will take longer to dispatch. Please refer to product description for lead times. 

I haven't received my item?

Please email us your name, order number and date of purchase.

We prefer email as it allows us time to research and respond.

Returns Information

We operate a 30 day refunds and return policy. 

If you change your mind you must return the product back to us within 30 days of delivery

Please include a copy of your invoice and a note stating reason for return. 

Additional keys, locks keyed alike or built to code are non refundable as they are personalised made to order goods.

Any refund, which is due to a fault or other defect, will include a refund of the applicable delivery charges otherwise not. 

It is the buyers responsibility to arrange the return of goods to us. We do not offer a collection service for returning items. 

Items must be returned including original product packaging and accessories.

We reserve the right to refuse any returns that do not comply with this policy.

Please post returns to the following address:

Home Secure (Online)

Unit 5, Brookfield Drive

Liverpool, L9 7AJ

United Kingdom

Frequently Asked Questions

An offset espag window lock is a locking mechanism commonly used in uPVC windows where the handle spindle is positioned off-centre. It secures the window by engaging multiple locking points along the frame.

The 250mm size refers to the overall length of the espag mechanism. Matching this measurement with your existing lock is essential for correct fit and smooth operation.

Common signs include difficulty locking or unlocking the window, a stiff handle, loose mechanism, or the window failing to close securely.

No, compatibility depends on factors such as spindle position, backset, and overall dimensions. Always compare your current mechanism before purchasing a replacement.

If your window becomes difficult to operate, doesn’t lock properly, or feels worn, the mechanism may need replacing. To learn more, read: Top Signs Your Window Mechanism Needs Replacing (And What to Buy)