The bracket is made with 3/8" thick acrylic, with a 1/2" diameter handle.  It's designed to sit in 8-9" of water. The heaters are loaded into the acrylic bracket and lowered into place carefully. You will need to make sure the length of the heaters won't be a factor, and be aware of the cords so everything tucks in nicely and stays positioned properly. Ideally once installed, you won't have to touch it until you need to do deep cleaning in the sump.

This bracket needs 2" of space to fit.

Dimensions:
8" wide x 1.75" deep x 10" tall
Holds up to three 1" diameter heaters

The heaters will not melt the acrylic. I've included some pictures of my own setup that has been in place since March 2020 - I'm using 300w heaters, they come on twice per day.