Why is this grid placement system 1x1?

This is a script that allows you to place block where ever you want them to be at be i want the gridstuds to be 4x4 not 1x1 but i don't know why it is 1x1 tried to change it but can't figure it out.

Heres the script + it is a localscript located in the startergui:

game:GetService("RunService").RenderStepped:connect(function()
	if Selected then
				
		local PlaceCFrame, X,Y,Z = nil, (Selected.Hitbox.Size.Z/2)%1, Selected.Hitbox.Size.Y/2, (Selected.Hitbox.Size.X/2)%1
		local p = ((CFrame.new(Mouse.hit.p, Camera.CFrame.p)*CFrame.new(0,0,-0.1))).p
		
		if Rotation0 == 0 then X,Z = (Selected.Hitbox.Size.X/2)%1, (Selected.Hitbox.Size.Z/2)%1 end
		
		Selected:SetPrimaryPartCFrame(CFrame.new(math.floor(p.X)+X,math.floor(p.Y+Y),math.floor(p.Z)+Z)*CFrame.Angles(0,math.rad(Rotation), math.rad(Toration)))
	end
end)