Called a knuckle duster revolver because, once empty, the gun was designed to be turned around in the hand and used like brass knuckles. The maker called them "My Friend," and that's how they are marked. They were very popular in the .22 Short chambering (as shown below).

One like this was featured in The Quick And The Dead, being held by Sharon Stone in preparation for shooting Gene Hackman from under the dinner table.

[Linked Image from cdn2.bigcommerce.com]