I tried the Tri Recs and it worked ok, but the Deb Tucker is my favorite for TIS units. You make them a tad oversized, then trim them down. She calls it the V-block trimmer. I'm in the process of making Liz Porter's "Emily's Wedding Quilt" for our oldest niece and have used the V-block trimmer A LOT. Every unit comes out the right size with the perfect quarter inch seam allowance.