MSMA (monosodium methanearsonate) is an arsenic-based grass killer. It kills grassy weeds such as crabgrass and goosegrass without harming most turfgrasses. It contains organic arsenic that, according to the University of Tennessee Extension, is less harmful than aspirin.
There are several styles of hearing aids available, from the smallest - Invisible in the Canal (IIC) to the largest and strongest - Power Behind the Ear (BTE), and the very popular Receiver in the Canal (RIC) - made to fit most hearing losses while remaining nearly unseen.
Completely in the canal hearing aid types, or CICs, refer to those in-the-canal products which are specifically manufactured to sit deep within the ear canal. A well-manufactured CIC may really be invisible, even when the ear containing the CIC is viewed side-on.