The package has 8 different sizes of heat resistant strips that allow you to make bias stems from 1/8"- to 1/2"-wide. Each size is a different color. The bars are smooth to make moving the bar inside the stem easier. Karen Kay Buckley's instructions are included in the package.
Also look for Perfect Circles and Perfect Ovals.
#186 Blanc Replacement Bobbin
#185 Ancient Scroll Replacement Bobbin
#181 Nightscape Replacement Bobbin
#178 Poolside Replacement Bobbin