Most vendors will say the largest spiral coil available is 2” (50mm). This may be the case for many, but that is incorrect. There are larger spiral coils available in the market, the largest being made out of aluminum or wire. In plastic, the largest spiral coil is 3.5” (88.9mm), and in aluminum or wire the largest spiral coil is 4.5” (114.3mm).
Larger diameter spiral coils can be manufactured in various pitches (holes per inch), but it is recommend to use either a 2.5:1 or a 2:1 pitch. By having less holes per inch, it will be easier to insert the spiral, and less material would be used.