I use a Soundback Adjustable 2.0 when playing with rock bands in a situation when I can't use my in-ear monitors. For normal function band gigs I use a clip-on microphone and IEMs, but this is a lifesaver when it's not practical to set up that much equipment.
The Soundback collapses down and fits easily into the mute bag of my Torpedo Classic, and slots over most commonly used dynamic microphones (SM58 style). The rubber collar ensures that it doesn't slip. The Soundback can be opened fully to provide maximum feedback to the player (and reduced sound to the audience, bandmates in front, and other mics), or (as pictured) left at various degrees of openness to allow more of the player's unmiced sound to reach the audience. I use mine fully open. This, combined with musicians' earplugs, allows me to protect my hearing but still hear enough of my sound to be able to play without overblowing. A surprisingly effective piece of kit.
