This fitting is specifically designed to be used to adapt Schedule 40 pipe to vacuum inlet valves...
Buy it:
$2.95 at Central Vacuum Factory
Featured Stores:
$64.67 at Faucet Depot
$67.90 at FaucetDirect.com
$69.85 at The Home Depot
$64.67 at Dirt Cheap Faucets
$67.70 at eFaucets.com
