The CH 34 is the US Army version of the Sikorsky S-58 Helicopter. It was originally intended to be used for anti sumarine duty, but saw a lot more action than that. The Westland Wessey is a license built veriosn from the UK.
I think this model kit looks very good, good details, no flash, maybe a bit short on exatly which version it is, but I think it is probably the CH-34A.