The Clipsal 755LPSMA4 Photoelectric surface mount battery powered alarm incorperates a sealed-in lithium battery with a 10 yr life time, so no need to replace batteries. The new stylish low profile design blends into any decor and is easy to use with large test/hush button. The robust digital electronic design offers superior performace and resilience. With built-in wireless interconnection, the product offers superior flexibility connecting to other 755LPSMA4 units and Clipsal 755 series mains powered smoke alarms. Providing simple and cost effective upgrades for an existing install, or add aditional alarms for increased protection or utilise this alarm to upgrade installs to meet the new regulations for interconnected alarms throughout the home. Functions/Features: Photoelectric technology for faster response to the most common fire type (smouldering fires) Sealed-in Lithium Battery with 10 year life Low profile modern design blends into any decor (only 37.5mm deep, 130.3mm diameter) Built-in wireless interconnection, compatible with 755RFB2 surface smoke alarm mouting bases. Quality sensing chamber with stainless steel insect screen (with 0.8mm mesh) for dust and insect ingress protection.