Large Knob: We designed the "Large Knob" to be used primarily on bikes with Oversize handlebars or with bars that do not have a crossbar.
However, it is possible to use this knob on "crossbar-type" bars as long as there is enough clearance for it to physically fit, which is determined by where the crossbar is, relative to the stock knob. Many bikes with crossbars require the smaller knob as the large knob will not clear the crossbar. The larger knob makes it a little easier to make quick changes on the fly.
The Large Knob price includes all the parts required to make it functional into your existing stabilizer, including a new stainless steel spring and ball for your base valve, and Allen wrenches.