A little effort has been made to improve reliability of a two non-identical unit systemusing the concepts of inspection, guarantee and replacement. Initially one unit (unit-1) isoperative and the other unit (unit-2) is kept as spare in cold standby. Each unit has two modes -Normal and Failure. Unit-1 has facility of pre and post inspection but if unit-2 fails, it goesdirectly to the repair. On failure of unit-1, pre-inspection is carried out to check whether thefailed unit is under guarantee period or not. If unit is under guarantee period then it is replaced
and re-installed. If unit is out of guarantee period, then it is repaired by repairman. After therepair of unit-1, it goes for post- inspection to decide whether the repair is perfect or not. If therepair of unit is found to be perfect then the repaired unit becomes operational, otherwise it issent for post repair while as Unit-2 becomes as good as new after repair. A single repair facility
is available to repair the system. The repairman cannot leave the system before completion of therepair of the failed unit. The failure time distributions of unit-1 and unit-2 and inspection timeare taken as taken as exponential. The istribution of time to repair of unit-1 and unit-2 andreplacement time are assumed to be arbitrary. Various important measures of systemeffectiveness have been studied extensively.