Bel-Art &ldquo;C&rdquo;-Shape Open 2.0lb Lead Ring Flask Weight with Vikem Vinyl Coating; For 1000-4000ml Flasks (F18308-4000) fits glassware 1000 - 4000ml flasks The open ring is made of lead and covered with Vikem vinyl and fits over side arm flasks without disconnecting tubing and affecting any processing Secure labware in water baths; adjusts to larger flasks and other lab apparatus where a closed ring might not fit Great for stabilizing large glass cylinders; vinyl coating protects researcher and easily-scratched glassware Ideal for fluid handling set-ups already in place-no need to disconnect in order to stabilize