Verizon and most cell-phone companies. Seriously! What mentalists used to pay hundreds of dollars to Nelson or Tucker for, most folks now carry in their pockets, gadgets that can do more, and take up a lot less space.
Kerry Pollock made a thumper especially for mentalists a few years ago that wprked beautifully.Don't know if he still has them. If interested,contact me off-line at "LMiller341@webtv.net"and I'll give you contact info. Larry Miller