This is the model with the notch under the B string.
The guitars that have become synonymous with Charlie Christian are the Gibson ES150 and ES250. The ES150 was produced in 1936 and was Gibson's first association with the standard electric guitar. Charlie Christian adopted the ES150 in 1937 as his guitar of choice.
The development of the pickup enabled the guitarist to become a fully fledged member of the group no longer limited to the rhythm section or having the band quiet down during solos. Charlie had something to say and at last his voice could be heard. In 1939 the ES250 was produced. Charlie received his ES250 in April 1940 Christian played these guitars until his death in March 1942.
Underlying this early technology was the pickup first developed by Gibson for use on a Hawaiian guitar. Next came the ES150, later a model with a notch in the blade under the 2nd (B) string was produced, finally the ES250 was made with 6 poles, one for each string. It is these pickups that create the sound that is associated with these guitars - and of Charlie Christian.