New Magic Item: Wardingbell

So here's an item I've submitted to the OSR Superstar contest that's running out there in OSR land:

Wardingbell

A wardingbell is commonly used by people with a desire for secrecy, privacy, and protection.  Wardingbells appear much as any other ordinary bell, but do not have a mechanism to cause the bell to actually ring.  Typically they are installed near doors, in hallways, and on gates, although they have found creative uses among adventurers who occasionally mount them on poles as a protection while camping.  Wardingbells must remain stationary for 1 hour before they activate.  Anyone not specifically named by the owner of the wardingbell when it is installed will have difficulty passing through the area it protects.  A wardingbell affects a 20' radius area.  Any character passing through this area must make a saving throw at a -2 penalty.  If the save is successful, the character feels a little strange, but can pass through the wardingbell's area of effect.  If the save is failed, the character will stop in his tracks, paralyzed.  This paralysis lasts for 1d6x10 minutes.  The Referee may decide what effects paralysis has in his or her game, but it is recommended that the character is frozen in place, unable to move or act.  The character is considered helpless and may only take mental actions.