New Kayak!

Hello Fellow NCKAers.  I'm new to this forum so bare with my noobness.  I am finally getting a kayak tomorrow.  It's a Cobra Explorer but doesn't have a seat.  My question is, are kayak seats generally universal in terms of size?  If they are which ones are best?  I checked out a few online at Amazon and there are some that seem quite nice.  I don't mind spending enough for I expect to be out on the water for quite some time for each trip I make on the yak, so i need something that will have some support and will be comfortable.  Thanks for any input!

-Chao