As the name might suggest he's a rat, mainly grey with a brown back & tail and four pink feet, each attached by a ball joint to legs which are molded into the body. The tail is hinged (up & down) at the point where it joins the body. So not God's gift to articulation then. His case brother Razorbeast has somewhat more meaningful articulation.
TF: Flipchanger: Pulling the tail up and unlocking it from the body causes the sides of the rat to fold open, the beast head to fold down underneath and onto the robot chest - revealing the robot head - and the robot legs to extend out the back of the toy. The arms are then pulled off the pegs that hold them in place in beast mode, then the gun halves can be removed from beside each hip and slotted together (has anyone got a spare of the half with the handle on it ?)
Robot has standard BW articulation - ball joints at the neck, shoulders, elbows, hips and knees. The chest and head are the rat grey, with the upper limbs and body (under the rat head chest) a brown, and the lower limbs painted silver. Head is another aborted lightpipe, which is a real shame in this case because the top of the head looks like an exposed brain - picked out in silver here - and that would have looked cool in clear plastic. As I mentioned his weapon is a 2 part assembly job - this type of weapon I associate with flip changers (because of the 2 jets and the racing car molds) yet Rattrap is one of only two BW Flipchangers to have it.
Overall: OK if stationary beast mode. Robot mode somehow packed with character (it's the head I think) even before the words "We're all gonna die" were uttered for the first time ! Worth getting if you can find one cheap