16th

so 1 = 100% of the explosion radius will break

DestroyJointRadiusPercent
number
Read Parallel
Used to set the proportion of the Explosion.BlastRadius, between 0 and 1, within which all joints will be destroyed. Anything outside of this range will only have the Explosion force applied to it.

For example, if Explosion.BlastRadius is set to 100 and DestroyJointRadiusPercent is set to 0.5, any joints within a radius of 50 studs would be broken. Any joints between the ranges of 50 and 100 studs wouldn't be destroyed, but the Explosion force would still be applied to the BaseParts.

This property allows developers to make Explosions 'non-lethal' to Humanoids by setting DestroyJointRadiusPercent to 0. This means the neck joint will not be broken when characters come into contact with the Explosion.

the scale of it is based on 0-1 not 0-100

its so the welds break, making the stuff explode in a similar way to the pot in the gif if arranged correct