Good tin openers. I used to buy in the P38 and P51 Shelbys and sell them here and BritishBlades at cost. My memory may be a bit skewed, but the smaller P38 was issued to individuals and reckoned to take about 38 twists to open a US issue ration can, and the larger P51 to catering staff to open the larger catering cans in 51 twists. However, the P51 came later, so I’m not too sure. The P51 is highly copied, the P38 being very small and fiddly to use.The shelby P-51 tin opener on e bay, they do a larger 2" one, good quality and as good as any i was ever issued !