"Simple and straight forward to refit in place of the old one, like almost any other immersion thermostat on the market. They all follow the same design if there intended for standard immersion elements, un-vented cylinder immersion elements have different features and dimensions although they do essentially the same job. More pricey from screwfix than at most trade wholesalers or retailers but most are not open after 17:00. Sadly screwfix branches are open to the general public which always makes a branch visit later in the day frustrating as they close the trade side and only operate the standard screwfix counters which leaves you queuing behind the hapless diy bodgers and the soccer mums buying light fittings and other stuff they don't know they don't need or how to fit. This replacement had an overheat cut off that the original did not have and its always better to fit one with this additional safety feature. only gave 3 stars for performance and reliability as only time will tell."