Brunton echo zoom monocular 10 30x21 description the echo 10 30x21 zoom monocular from brunton is an ultra compact optical device designed for momentary glassing applications this handheld scope features bak 4 prisms and multicoated glass elements that transmit bright images rich with contrast and detail the 10 30x magnification is suitable for a range of intermediate to long range observations the monoculars size makes the echo small enough to comfortably fit in a cargo pocket or sid