WonderFil Specialty Threads DecoBob Black #101. DecoBob thread carries a textured matte finish that has been treated to behave more like cotton and eliminate stretch. Delicate but incredibly strong, this lightweight thread ensures stitching becomes less bulky and designs softer while the fine weight also allows for more acute miters and rounder and smoother curves. DecoBob is also an ideal bobbin thread and is available in Class 15, L and M size pre-wound bobbins in reusable plastic casings.