Hard to tell from the photos how big they are. I measured them at approximately 10mm x 8mm x 6mm. When closed, they are about the size of a telephone cord button. The same compression tool works with both, although the vise does the job quite adequately. I had a hard time arranging the wires inside the case before actually connecting them. The device is small and next time I use it I will use 24AWG not 22AWG. I will buy one size bigger (T-22). I hope the slightly larger slot will make routing the wires easier.