Trying to get the height of the left leg?

I'm making a tower defense game, and i'm not sure how to get the height of the left leg of a rig. Any help? (Line 82)!

local Players = game:GetService("Players")
local PhysicsService = game:GetService("PhysicsService")
local ReplicatedStorage = game:GetService("ReplicatedStorage")
local RunService = game:GetService("RunService")
local UserInputService = game:GetService("UserInputService")

local modules = ReplicatedStorage:WaitForChild("Modules")
local health = require(modules:WaitForChild("Health"))

local money = Players.LocalPlayer:WaitForChild("Money")
local functions = ReplicatedStorage:WaitForChild("Functions")
local requestTowerFunction = functions:WaitForChild("RequestTower")
local spawnTowerFunction = functions:WaitForChild("SpawnTower")
local towers = ReplicatedStorage:WaitForChild("Towers")
local camera = workspace.CurrentCamera
local gui = script.Parent
local map = workspace:WaitForChild("Grassy")
local base = map:WaitForChild("Base")
local info = workspace:WaitForChild("Info")

local hoveredInstance = nil
local selectedTower = nil
local towerToSpawn = nil
local canPlace = false
local rotation = 0
local placedTowers = 0
local maxTowers = 15

local function SetupGui()
	health.Setup(base, gui.Info.Health)
	
	workspace.Mobs.ChildAdded:Connect(function(mob)
		health.Setup(mob)
	end)

	info.Message.Changed:Connect(function(change)
		gui.Info.Message.Text = change
		if change == "" then
			gui.Info.Message.Visible = false
		else
			gui.Info.Message.Visible = true
		end
	end)

	info.Wave.Changed:Connect(function(change)
		gui.Info.Stats.Wave.Text = "Wave " .. change
	end)

	money.Changed:Connect(function(change)
		gui.Info.Stats.Money.Text = change.."$"
	end)

	gui.Info.Stats.Money.Text = money.Value.."$"
end

SetupGui()

local function MouseRaycast(blacklist)
	local mousePosition = UserInputService:GetMouseLocation()
	local mouseRay = camera:ViewportPointToRay(mousePosition.X, mousePosition.Y)
	local raycastParams = RaycastParams.new()
	
	raycastParams.FilterType = Enum.RaycastFilterType.Blacklist
	raycastParams.FilterDescendantsInstances = blacklist
	
	local raycastResult = workspace:Raycast(mouseRay.Origin, mouseRay.Direction * 1000, raycastParams)
	
	return raycastResult 
end

local function RemovePlaceholderTower()
	if towerToSpawn then
		towerToSpawn:Destroy()
		towerToSpawn = nil
		rotation = 0
	end
end

local function CreateRangeCircle(tower)
	
	local range = tower.Config.Range.Value
	local height = (tower.PrimaryPart.Size.Y / 2) + tower["Left Leg"].Height.Y
	local offset = CFrame.new(0, -height, 0)
	local p = Instance.new("Part")
	p.Name = "Range"
	p.Shape = Enum.PartType.Cylinder
	p.Material = Enum.Material.ForceField
	p.BrickColor = BrickColor.new("Electric blue")
	p.Size = Vector3.new(2,range * 2, range * 2)
	p.TopSurface = Enum.SurfaceType.Smooth
	p.BottomSurface = Enum.SurfaceType.Smooth
	p.CFrame = tower.PrimaryPart.CFrame * offset * CFrame.Angles(0, 0, math.rad(90))
	p.CanCollide = false
	p.Anchored = true
	p.Parent = workspace.Camera
end

local function AddPlaceholderTower(name)
	
	local towerExists = towers:FindFirstChild(name)
	if towerExists then
		RemovePlaceholderTower()
		towerToSpawn = towerExists:Clone()
		towerToSpawn.Parent = workspace.Towers
		
		for i, object in ipairs(towerToSpawn:GetDescendants()) do
			if object:IsA("BasePart") then
				PhysicsService:SetPartCollisionGroup(object, "Towers")
				object.Material = Enum.Material.ForceField 
			end
		end
	end
end

local function ColorPlaceholderTower(color)
	for i, object in ipairs(towerToSpawn:GetDescendants()) do
		if object:IsA("BasePart") then
			object.Color = color
		end
	end
end


gui.Towers.Title.Text = placedTowers.. "/" ..maxTowers
for i, tower in pairs(towers:GetChildren()) do
	if tower:IsA("Model") then
		local button = gui.Towers.Template:Clone()
		local config = tower:WaitForChild("Config")
		button.Name = tower.Name
		button.Image = config.Image.Texture
		button.Visible = true
		button.LayoutOrder = config.Price.Value
		button.Price.Text = config.Price.Value.."$"

		button.Parent = gui.Towers

		button.Activated:Connect(function()
			local allowedToSpawn = requestTowerFunction:InvokeServer(tower.Name)
			if allowedToSpawn then
				AddPlaceholderTower(tower.Name)
			end
		end)
	end
end

local function toggleTowerInfo()
	if selectedTower then
		CreateRangeCircle(selectedTower)
		gui.Selection.Visible = true
		local config = selectedTower.Config
		gui.Selection.Stats.Damage.Value.Text = config.Damage.Value
		gui.Selection.Stats.Range.Value.Text = config.Range.Value
		gui.Selection.Stats.Cooldown.Value.Text = config.Cooldown.Value
		gui.Selection.Title.TowerName.Text = selectedTower.Name
		gui.Selection.Title.TowerImage.Image = config.Image.Texture
		
		local upgradeTower = config:FindFirstChild("Upgrade")
		if upgradeTower then
			gui.Selection.Action.Upgrade.Visible = true
			gui.Selection.Action.Upgrade.Text = "UPGRADE: " ..upgradeTower.Value.Config.Price.Value.."$"
		else
			gui.Selection.Action.Upgrade.Visible = false
		end
	else
		gui.Selection.Visible = false
	end
end

gui.Selection.Action.Upgrade.Activated:Connect(function()
	if selectedTower then
		local upgradeTower = selectedTower.Config.Upgrade.Value
		local allowedToUpgrade = requestTowerFunction:InvokeServer(upgradeTower.Name)
		
		if allowedToUpgrade then
			selectedTower = spawnTowerFunction:InvokeServer(upgradeTower.Name, selectedTower.PrimaryPart.CFrame, selectedTower)
			toggleTowerInfo()
		end
	end
end)

UserInputService.InputBegan:Connect(function(input, processed)
	if processed then
		return
	end
	
	if towerToSpawn then
		if input.UserInputType == Enum.UserInputType.MouseButton1 then
			if canPlace then
				local placedTower = spawnTowerFunction:InvokeServer(towerToSpawn.Name, towerToSpawn.PrimaryPart.CFrame)
				if placedTower then
					placedTowers += 1
					gui.Towers.Title.Text = placedTowers.. "/" ..maxTowers
					RemovePlaceholderTower()
					toggleTowerInfo()
				end
			end
		elseif input.KeyCode == Enum.KeyCode.R then
			rotation += 90
		end
	elseif hoveredInstance and input.UserInputType == Enum.UserInputType.MouseButton1 then
		local model = hoveredInstance:FindFirstAncestorOfClass("Model")
		
		if model and model.Parent == workspace.Towers then
			selectedTower = model
		else
			selectedTower = nil
		end
		
		toggleTowerInfo()
	end
	
end)

RunService.RenderStepped:Connect(function()
	local result = MouseRaycast({towerToSpawn})
	if result and result.Instance then
		if towerToSpawn then
			hoveredInstance = nil
			
			if result.Instance.Parent.Name == "TowerArea" then
				canPlace = true
				ColorPlaceholderTower(Color3.new(0,1,0.6))
			else
				canPlace = false
				ColorPlaceholderTower(Color3.new(1,0,0))
			end
			local x = result.Position.X
			local y = result.Position.Y + towerToSpawn.Humanoid.HipHeight + (towerToSpawn.PrimaryPart.Size.Y / 0.65)
			local z = result.Position.Z

			local cframe = CFrame.new(x,y,z) * CFrame.Angles(0, math.rad(rotation), 0)
			towerToSpawn:SetPrimaryPartCFrame(cframe)
		else
			hoveredInstance = result.Instance
		end
	else
		hoveredInstance = nil
	end
	
end)