There are 2 apps we think work great with this message: Bitly and Calendly.
Bitly allows you to shorten URL's, and track the amount of clicks that each click gets. This can be super-helpful because at the end of running your campaigns for 1 week, or so, you can log in to your bitly dashboard and see which links got the most clicks.
More info on that here: https://bitly.com/
Calendly is also super awesome because it gives interested prospects a chance to schedule a meeting with you. By including a Calendly link in your LinkedIn message, you can get the prospect closer to purchasing your product or service.
More info on that here: https://calendly.com/