WntrMute is right - they come with a conventional plastic film strobe disk. It's not a high-quality part - just a throw-in like the bubble level and Shure tracking gage that come with every VPI table. I nailed mine to the wall as soon as I opened the box. It's not good enough to get the most out of the SDS. Like almost all disks of this type, it can only work under fluorescent lighting. This is because it is only accurate when the house AC is delivered at precisely 60.00hz. Just like every 'phile knows that household AC varies in the actual voltage your equipment is fed, the frequency also varies. When a record speed varies even a tiny bit from 33.333 or 45 RPM, the pitch of all the music is altered, and the music is degraded. The VPI SDS is designed to regenerate its own clean power and pass along a rock-solid stream of current at a constant frequency to the motor. In fact, the SDS controls the speed of the motor with extreme precision in response to the setting you dial in through its up/down arrows while watching the strobe disk, and is shown in hz in a large LED.
Digital strobes like the KAB avoid the problem altogether by providing a small hand-held battery-powered laser that modulates its highly-accurate disk at precisely 60hz. When you use this tool to set the SDS output frequency, perfect rotational speed is assured. The SDS is throttled by an inaccurate reference. When you finally get the bars to stand still, your actual platter speed rarely be any better than close to 33 1/3.
I conclude that anyone thinking about spending $1200 for this turntable upgrade should also add a budget to get the most out of it. This includes good power cords and some attention to vibration control in addition to a digital strobe. If you are not interested in this much precision or you really only want to change from 33 to 45, you may wish to look for an earlier VPI speed box called a PLC on the used market. They are usually priced around $200, allow instant changes from 33 to 45, and sound better that just plugging directly into the wall. Pro-ject has a min-SDS for around $650 new that would be in the middle.