Bulk is the package size of NTC thermistors. It's in the Bead, Epoxy package for convenience. To make NTC thermistors work, the resistance tolerance is ±10%. The temperature of NTC thermistors should be set to 150°C in order to ensure reliable performance.
DC503J2K Features
Package/Case: Bulk DC Series Operating Temperature: 150°C Mounting Type: Free Hanging
DC503J2K Applications
There are a lot of Littelfuse Inc. DC503J2K NTC Thermistors applications.