Where can you get big heat mats

I am trying to find a big heat mat, like one you can put into a 120 gallon. Biggest I can find is 18 by 8 inches, which is like a ninths of the tank is there a mat that is like 12 by 24 inches?

If you go to Petmountain.com
You can get a Flukers Large Heat Mat: 11" x 17" or Flukers Jumbo Heat Mat: 11" x 29"

I would not put them inside my terrariums and always keep them on a thermostat. :)

Most people would run flexwatt for under cage heat or use a RHP in a larger enclosure.

I use Ultratherm heat pads from The Bean Farm you can get those in many sizes ready to go.... With and Without Thermostats

They also carry Kane heat pads, Rhp's and Flexwatt make your own size stuff

https://beanfarm.com/collections/heating?page=3

I would use 11" heat tape cut to the length I want. Reptile Basics will also wire it up for you.

It would go under the tank and yes use a thermostat.

11" wide- Flexwatt x 24" long (or similiar brand of heat tape) would be my choice as well...(as above). I've used the actual brand Flexwatt for decades now, haven't had
try any of the "look-alikes" yet. And just to reiterate, it's called "UTH" because it must go outside the tank, underneath, & yes, you need to regulate it too.
(UTH = under tank heat)

Thanks for all the suggestions, i have never use any other heating stuff beside UTH, and different types of lamps. so I don’t feel comfortable using RHD or anything else. Bean farm and flukes heating mat looks great but the shipping is quite expensive. A ten day shipping for 45$ is not very good. Can I get those heat mats from amazon.ca? Can you guys link them. I can’t find it. Thank you so much