We call those a "gopher getter" or "burrow builder." Used at the right time of year, they're very, very effective. The bait we use here is oat bait, with 2% strychnine and maybe some cane sugar dust mixed in to get them to eat more of it. When I've used a gopher getter, I make passes between 25 and 50' apart, depending on the gopher mound density. I've gotten up to an 80% kill rate.

Best time of year here in Nevada to use it is in April, when the frost comes out of the ground, but there is still enough moisture to hold the burrow/tunnel open before irrigation season starts.

If I had a big infestation of pocket gophers to clear out, a gopher getter and 2% strych bait would be my first tool to use.