Parts size dimensions get set to the x value of the given size

ok so im trying to make a part with a bindableevent, there is a passed size value and it sets the parts size to it. however it seems to set the x, y and z values of the parts to the x value of the passed value.

Heres the script:

game.ReplicatedStorage.ServerHitbox.OnInvoke = function(part,size,player)
	local weld = Instance.new("WeldConstraint")
	local Hitbox = script.Hitbox:Clone()
	weld.Parent = Hitbox
	Hitbox.CFrame = part.CFrame
	weld.Part0 = Hitbox
	weld.Part1 = part
	Hitbox.Parent = workspace.Hitboxes
	Hitbox.Size = size
	print(Hitbox.Size)
	Hitbox:SetAttribute("IsServersided",true)
	Hitbox:SetAttribute("Owner",player.Name)
	return Hitbox
end

help would be greatly appreciated!!!