The ZYYX SoftSpring is an accessory for use when you are printing with softer materials. This can be ZYYX Flex or other flexible materials such as TPU, TPE, NinjaFlex, or soft PLA. For more info check here.
ZYYX Pro II: No
ZYYX Pro: Yes (not with BT1-Pro upgraded extruder)
ZYYX/ZYYX Classic: Yes