The STX Sync Tour putter was a new thought in putter design from around 1997. Rather than being weighted out at the periphery of the putter's face, its mass is concentrated at the center:

        +--+             +-------+
        |  |             |       |
        |  |             |       |
        |  |             | +-----+
        |  +---+         | |
        |      |         | |
        |      |         | |
        |      |         | |
        |  +---+         | |
        |  |             | |
        |  |             | +-----+
        |  |             |       |
        +--+             |       |
                         +-------+
        STX         Conventional weighting


The theory behind it is that there are two different types of putt strokes. One style tries to keep the putter's face perpendicular to the line of the putt throughout the stroke. The other style allows the face to open on the backswing, and closes to perpendicular during the downswing. Conventional perimeter weighting creates more of a moment of mass for the putter's face, and inhibits the open/close putt style. The STX Sync Tour has a low moment of mass, and is more suited to the open/close putt style.