I prefer a dark and opaque color as clear and light-coloured spirals can get tinted overtime and look dirty. Slim invisibobbles seem to stretch a bit more than Originalbut a Slim is prettier at first, probably lighter (to avoid traction alopecia and pain) and require probably less polyurethane/artificial resin (so they're more eco-friendly). When it’s not in my hair I keep it around my wrist to always have access to it, I like that it is non-soaking and durable, if it is too stretched I use heat (placing it in hot water) it is not a miracle solution but it helps a little.
