This is a quality medical grade 3 blade rectal speculum. Works very smoothly. Allows for interesting exploration into dark places! Can be locked open using thumb set screw. 
The probe section is about 3.5 inches long, and is 3/4 inches in diameter when closed. When opened the prongs spread to a maximum of 2.5 inches apart. 
Best used with a good quality lubricant either waterbased or silicone lube.