O'Sullivan-O'Connor Vaginal Retractor with three interchangeable blades German Made This is an amazing vaginal retractor/speculum with four blades. All four blades spread the hole open with a ratcheting action. The two thicker blades are interchanged and adjusted by means of a wing nut. Three blades are included: small, medium and large. Two of the blades are shown installed with the third to the side. This can open a hole right up with an unparalleled level of access inside. If you want the best view possible into someone this is the way to go. A little uncomfortable but that's the price one pays for visibility. Dimensions: Inside diameter of circular frame at maximum expansion 3.75 inches Blades sizes ( length x width one each included ) Large : 3.5 x 1.75 inches Medium: 3.25 x 1.5 inches Small: 1.73 x 0.75 inches