This is an ingenious and very useful $25 accessory for anybody who owns Sennheiser MD 421 microphones and is perpetually frustrated at the poorly-designed mic clip/mount, the one that results in the mic falling off the clip and needing to be duct-taped to stay in place. MicLock is a small, molded piece of high-density plastic that fits over the end of your 421 and once in place, stays with the mic and makes it impossible for the mic to separate from the clip/mount. You will want to buy one for every 421 you own.
($24.99 direct,
themiclock.com)