You have to cut them yourself. The strings should sit about halfway in, like this:
.--.
---------| \---------
`--'
The diameters of each groove should approx match the diameter of each string - and be careful that you hold the bridge the correct way around, because they are not symmetrical (i.e. make sure that you're putting the widest groove into the bass side of the bridge).
Comments
You have to cut them yourself. The strings should sit about halfway in, like this:
The diameters of each groove should approx match the diameter of each string - and be careful that you hold the bridge the correct way around, because they are not symmetrical (i.e. make sure that you're putting the widest groove into the bass side of the bridge).
If you don't have some tools already to cut the grooves of various diameters, buy yourself a set of welding tip cleaning files for ~5 bucks e.g. https://www.amazon.com/Letool-Stainless-Welding-Cleaner-0-38-1-54mm/dp/B014D1M62G/