The aims of this study were to determine the efficacy of the KontrolFlexTM AccufileTM compared to the READY•STEEL™ Flexofile® using an electronic apex locator and to evaluate the instrument’s design via scanning electron microscopy. Actual canal lengths of thirty extracted teeth were determined under magnification. An alginate model was used to determine experimental canal lengths with the Root ZX II apex locator and size #10 Accufiles and Flexofiles. Differences between actual lengths and experimental lengths were compared with Student’s t test. The average experimental lengths were short of the actual length by -0.10 mm (±0.34) and -0.12 mm (±0.16) for the Accufile and Flexofile, respectively with no statistical difference (p > 0.05). SEM images revealed similar non-cutting “batt” tips and a square cross-section for the Accufile and triangular for the Flexofile. Both files provided similarly high levels of reliability when used with the Root ZX II electronic apex locator.