Yes, it is quite well hidden in the section labeled
inswool and insboard 
Seriously, HTT&R is a great one stop shop for all your forge supplies.
One item often overlooked is the quick connect fittings for the propane hoses. This will allow you to just unhook the hose as you would an air hose. You can switch to line to another forge, propane device, or the propane fired shop heater in seconds, and it makes putting the forge and the propane away much simpler and safer. If you use a bulk 100# tank that is outside ( where it hopefully should be), it really is a necessity.
Insboard is also a real boon for making front and back walls on forges.
When building the forge, you have to fire the satanite, then patch any cracks, then fire it again, then coat with ITC-100, then fire to cure everything one last time. Making the ends from insboard will allow you to temporarily slip the back wall in place for firing, remove it for re-coating, and when all is ready for the final seal-up, just butter some satanite on the end of the wool lining that has already been cured, slip the end in place, use your fingers ( or a long round ended stick) to make a smooth ogee on the inside ... and let cure. The final firings to adjust the burner and such will cure that little bit of refractory. ( you can paint ITC-100 on the joint if you wish, too.)
A trick I use when doing the wool and floor shaping and coating is to put Saran-wrap over the back end and slide it in place at each build up. Thai makes the end of the wool sides fit perfectly against the back wall. Once the satanite, Bubble alumina, or ITC-100 is dry, I can slip out the back, take off the saran-wrap, slid it back in, and fire the forge to cure that layer.
For a super efficient forge, you can put two layers of insboard on each end, with a 1" Hi-Z inswool layer between them.
The trick with the saran-wrap along with the insboard and inswool sandwich works super well when fitting removable tops and/or bottoms on vertical forges.
