Replacement RECURVE Crossbow String.
50lb String - For the metal limb crossbows only, such as the Gekko or Komodo
80lb String - For the 80lb crossbows, such as the MK1 / Cyclone / ABS / Rapture / Scorpion 1 / Scropion 2.
80lb Cobra / Mantis String - For the Tomcat MK2 / Cobra / Mantis.
Regarding the two different 80lb strings, the difference here is they're made in different factories, but they're both the same size.
It's usually best to have the string from the same factory as the crossbow, although it shouldn't make much difference if they're not.
40lb / 105lb / 120lb / 150lb - This string cannot be used on 175lb crossbows.
175lb - This string can also be used on the 4 lighter draw weight limbs as well as the 175lb crossbow.
Regarding the rifle crossbow strings, they're both the same size as each other, the difference is the 175lb is thicker and stronger, so it can support the tension of a higher draw weights, as well as the lower draw weights. whereas the 150lb string is limited to 150lb and less.
Click this line for the version with the end caps.