Why would you need this? You put your foot on the brake, flip the switch which closes the valve, then you let off the brake and it leaves the fronts locked... Great if you have a manual transmission, but i've never had any issues doing a burnout with an Automatic vehicle in the past... Yeah it'd be cool to have a "burnout button" but I've also seen line lock kits malfunction and 800 horse dragsters going down the track with 2 locked front wheels.
Not worth it :imo:, I agree with Jared. Yeah it's cheap but it's pointless unless you race your truck.
Besides, as cool as burnouts are, tires get expensive, so it's not like you're gonna use it all the time unless you race and actually stage your truck properly with drag slicks/radials...