He is a robot created by Lisa in the episode "Snow Bored". When Lana shows Lisa the snowman she built, Lisa responds by introducing her new robot. Mr. Reinforced Titanium Alloy Arms then targets Lana's snowman and shoots lasers at it.
His body consists of a mailbox with the number 1216 imprinted, and two large dark grey arms (with grey 2-fingered claws on each arm) on either side of his chest.
The head is a metal cylinder with cutout red eyes with fully functioning eyelids. One side of Mr. Reinforced Titanium Alloy Arms' head has a lever that juts outwards, while the other has an L-shaped pipe object with a scanning device.
He has a pair of tank treads that go on either side of a metal box with the mailbox pole attached to it.
Mr. Reinforced Titanium Alloy Arms returns in the Internet exclusive short "Robot Sitcom", in which he is shown to have moved into Lisa's Underground Bunker with two of her other robots Todd and FriendBot 1000, along with a sentient toaster who is simply named Toaster and a beast named Tentacle. The short also reveals that he isn't waterproof.
According to Lisa, his lasers are programmed to destroy anything "jolly".