Nite Ize Figure 9 Carabiner Large Rope Tightener, Large, Black 4 Pack. There are 3 additional carabiners which we believe to be made of hard plastic.. they are Nite Ize as well. Those measure:  The 2 large ones are #4, 3.5"L x 1 - 1.5" w.  The small one is #2, 2"L x 1"w.