Clamp Retort - 4 Prong with Boss Head-EIS-CH0687 offers a thoughtfully designed, durable resource for hands-on learning. Includes: (1) Clamp Diecasted alloy clamp retort, cork lined jaws with bosshead whichÂÂ accommodates rods up to 15 mm dia. Jaw opening 90 mm. ThisÂÂ clamp holds items at a distance of 15 cm from support rod.