The case is suitable for panel flush mounting as well as plug in type Instruments like Temp. Controller, Temp Indicator, Timers, Counters and all other analogue and digital Instruments. Case has ventilation on three sides and on topside provision for sticker of Terminal connection diagram. Case can be flush mounted on panel by ring clamp, which takes grip on serration in Box. Cassette of case consists of variable Black Plate and Front Plate Joining it by two PCB Boards or Bakelite Sheet in between without any screw. When cassette assembly is slide in to the case it takes firm grip on Box by snap action of front plate and back plate on respective provision given on Box.. Four Models for different application is made by changing back plate on case keeping rest all assembly same. (1) Back Plate plain (IC - 248 - 03) makes it suitable with the help of clamp of flush mounting instrument. For applications With/ without Terminals on back. (2) Back Plate with 8 Terminals (IC - 248 - 04) makes Box suitable with the help of clamp a flush mounting instrument with (4+4) 8 terminals as an integral part. (3) Back Plate with 8 pins (IC - 248 - 05) makes it suitable for plug in instrument compatible with 8 pin Din Rail relay sockets. Clamps are not needed as it is a plug in module. (4) Back Plate with 11 pins (IC - 248 - 06) makes it suitable for plug in Instrument compatible with 11 pin Din Rail relays sockets. Clamps are not needed as it is a plug in module.