Please welcome Eyoyo Underwater Fishing Cameras.https://amzn.to/3siEgXn
I'd used a 4" for a lot of years untill I added a camera to go along with the flasher. Now I use a 5" to fit the camera down the hole better. Never lost a fish in the 4" for being too small. You can drill holes all day if necessary with these smaller augers without wearing yourself out. NBG
Didnt know lazer made a 4"
Can't argue with a nils but 6" will cover most anything you can catch