The number of certified OMS devices is growing. Five new OMS Generation 4 products have recently been added to the product listing: Maddalena’s “Arrow EVO” Wireless M-Bus radio module, two Techem "Measuring capsule heat meters" – type 4.1.1 and type 4.5.1 – and two models of Techem "Pulse radio interface radio 4" – one for heat meters and the other one for water meters. OMS certification ensures compatibility with the OMS specification and opens up a broad market for manufacturers of interoperable smart meters. There are currently 29 devices listed on the OMS website.