Please find below documentation that will help you operate your Casella product:
63x Series Sound Level Meter Handbook (English)
63x Series Sound Level Meter Handbook (French)
63x Series Sound Level Meter Handbook (German)
63x Series Sound Level Meter Handbook (Spanish)
63x Series Sound Level Meter Handbook (Chinese)
63x Series Sound Level Meter Field Guide (English)
63x Series Sound Level Meter Field Guide (French)
63x Series Sound Level Meter Field Guide (German)
63x Series Sound Level Meter Field Guide (Spanish)
63x Series Sound Level Meter Field Guide (Chinese)
63x Environmental Enclosure Datasheet (English)
63x Series Sound Level Meter Datasheet (India)