Originally the innovation of Winchester CEO John Olin as the perfect shotshell for his Model 21 double barrel, the Super X Mark 5 became the first 'modern' plastic shotshell in the early 60s.
 
Gauge - 16 Ga.
Load - 2 3/4", 1 1/8 oz. # 7 1/2 Shot
Package Quantity - 25 Shells