Who makes a good and easy to use safty harness? When it gets colder, does it go under your jacket? Thanks, Jim

Summit makes one called "Seat-O-The-Pants" which costs about $60. It's a complete body harness and also can go under your coat for cold weather hunting.
I finally bought one this year and I'm happy with it so far.

i've had my seat o the pant for three yrs now and it's lightweight and easy to use and you can't put a price on your saftey it's well worth the price!! and summit now has several different models to choose from!

The Hunters Safety System is one of the easiest to use but it's also one of the most expensive. ($99) It's a vest style with 4 buckles. Has pockets as well which are convenient.

Summit now makes a Seat O The Pants in a mesh vest style as well and it's less expensive than the HSS.

I use the Seat O The Pants harness that came with my Summit climber.

Seat of the Pants is a great system. you can put a jacket on over the harness without having to disconnect the harness to do so. I love being able to sit in my stand and toss my coat on as the sun starts to set and the temps drop and not worry about my harness.

I guess I will say that I also use the Seat-O-The-Pants that came with my Summit stand. It's very easy and comfortable to use. Only 2 negative points that I have about it:
1) If you use rain gear or a parka with a hood attached, the strap comes out of the side of the hood. Kind of a PITA.
2) The metal clip thingy that is used to connect to the tree strap is notoriously loud if it hits your stand. I dont' know about anybody else but mine always wants to get loose and bang into my stand when I'm setting up.
Other than that, its a great harness. I have even tested mine by purposely stepping off of my ladder stand about 5 feet up. Just wear tighty whities or you'll be singing in the choir.

Seat- o- the- pants here also. Can't be beat.

I have both, Seat o the pants (purchased) and the one that just came with my Summit treestand, the big difference is the way it attaches to your lanyard. The one that comes with your Summit has a "Rams horn" type hook (basically a curly q kinda of set up) and the purchased one has a true climbing carabeaner (sp?) I prefer the carabeaner type, but both are great and give me alot more confidence when I shoot. What G2 shooter said is true though, If you wear a hood the strap comes out of you hood about where your ear is. I dont know how that would be if you fell, i.e. jerking your head around, and I dont like to wear it over top of my coat, too hard to get into pockets and extra things to clink together.

I am a big fan of the Seat O The Pants. Here is a mini review I just finished on the newer version.
http://www.broadheadtests.com/FEATURES.html