A golf training aid for improving putting stroke and stance is transparent plastic in the shape of a tunnel, the bottom being open for placement on grass or carpet. A guide slot is formed by a rectilinear guide slot housing centrally disposed along the length of the upper wall and extending forward from the entrance opening, forming a neck. A black or opaque strip of plastic forms an extendable guide bar slidingly fitting within the guide slot. The extendable guide bar may be pulled forward a desired distance so as to increase the effective length of the device. Parallel opaque stripes are located along the length of the upper wall and spaced the diameter of a golf cup. The golfer evaluates putting stroke and ball travel relative to the guide bar and stripes.