i recently found a fish head spin i have never used or fished with one before and i want to know how many people use them how they like them when how and where you fish them and what kind of trailer people like to use i fish with spinner baits a lot and i am exited to use it and it seems like its popularity is growing fast

I love them and they do catch fish. I have got to where I will use instead of using a deep diving crankbait almost every time. I have been using the XB360 underspin with a swimbait on it.

Whacked some 5-7lbers suspended deep under bait in the dog days of summer with a guide on an East Texas lake using under spins.

what size do yall use?

what soft bait do you put on it

Fluke

Fluke, paddle tail, 3" inch Mann's Minnow, 5" Yum
1/4oz -- 3/80z -- 1/2oz

Some of the best ones out there, available in 3 different hook sizes and 4 different weights.

https://www.flatlandscustomtackle.com/store/p61/_Shimmer_Swimmer.html

^^^^ yep, these will catch em, and are great around timber because the arm of the spinner flexes and hops over limbs and branches

I will have to try an under spin.

why do they all use a "willow" blade?
One of the most successful underspins -- Blackmore Roadrunner -- uses a small Colorado blade.
I really like the underspins with a Colorado blade.
The 3/8oz Roadrunner is really good, but I still change out the blade to #5 custom Colorado blades.
I got some 1/2oz underspins from MT Pockets that I haven't tried yet but look good.

The 1/4oz and 3/8oz are also good shallow over and in newly flooded grass and brush.

I have been fishing 1/4oz Blackmore Roadrunner; White head with a Mann's 3" Black n Silver Minnow for a few years now. This is a very good lure on Lake Athens & Fork.

I like to use the 4" little dipper for a bait on it. I agree with Nutman that a little colorado blade makes a big difference.

I like to fish them in any water really but especially in marinas.

Last summer I caught a few really good fish on an underspin head with a 5" money minnow on it. I think anything you can do to add a little flash to a bait is going to help you get bites.