This is the size I used as well. There is a little room at the ends and sides of the trit. This space will be filled by the Norland or whatever epoxy you're using to set the trit.
Sabre375You're welcome. I used Norland 61 to set the trit in mine. This is an optical grade adhesive that is UV cured. For the curing I used a Nitecore TUBE UV. Hope this helps and good luck setting your trit. This is a great little light!