Wireless doorbells from the major manufacturers have improved greatly in quality over the last 10 years, the bell pushes are robust, the sound quality has improved along with reliability. Prices vary from £20 to £100 due to distance (from 50m to 500m), choice of bell pushes, sound volume (between 78dB and 90dB), range of melodies and the quality of finish (between white plastic and glass). All the brands have there niche - Jacob Jensen with their modern design, finish and sound, Grothe with their heavy duty commercial grade products, Byron with their outstanding choice and Honeywell-Friedland with their thoughtful design. Wireless products offer ease of installation, the benefit of multiple units operating from a single or several pushes and flexibility of positioning around the home (or the garden office). However, wireless signals are affected by metal, so bell pushes should not be placed on UPVC door frames (because of the metal security frame behind the UPVC frame), metal gate posts or where there is foil backed insulation in the path of the chime unit. Similarly some 434MHz systems can suffer interference in particular circumstances (although this is unusual), and the 868MHz models (these are generally the more expensive) do not suffer in this way.