Bought this from my local Screwfix yesterday, was £8.79, now £3.49. Used it to hammer in some fixing posts for a garden border yesterday, and did the job very well.
Whilst you can get heavier (4lb for example) hammers, these require more effort to lift etc, and I reckon the 2.5lb hammer is a good balance of weight and manageability.
Can also be bought online for an extra £5.00 p&p (or free delivery if you spend over £50) taking the total to £8.49.
Screwfix Product Details:
Product Code: 76956
Strong fibreglass shaft and chamfered edges with full polished striking face.
* Drop Forged Steel Head
* Bi-Material Soft-Grip Handle
* 2-Piece Construction