Compact and connected, the Sony HVL-F28RM External Flash is a sleek and portable flash featuring an impressive guide number of 92\' at ISO 100 and 50mm, along with a built-in 2.4 GHz radio transceiver to allow photographers to quickly create portable lighting setups with complete support for P-TTL / ADI metering. This flash can be set as a commander or a remote that fully supports Sony\'s existing radio commanders and receivers, including ratio control, the ability to work with up to 15 flashes in five groups. In terms of its physical design, the HVL-F28RM has a compact, pocketable design well-suited to the a7-series mirrorless bodies and has a 0 to 120° tilting head for flexible bounce control. Additionally, it sports a dust- and moisture-resistant construction along with a durable metal foot.