I enjoyed my DETacc on my 4K for many years, but it doesn't play well with the new amped batteries without a bit of jigging in the battery.
Like mardymoose below, it also has an on/off switch and volume control. The difference between the two is mine hooks up 'before' the battery, and the RB one hooks up 'after' the battery.
DETacc are in the process of releasing a new version (perhaps to overcome this issue???)...it was due last Oct, so i don't know where it's at this point in time.
It's the only one i've tried so i will leave it to others to regale their versions..
Cheers