years (only because I've met people taking their 5th one, which is kind of sad since they haven't been promoted out of it - officers lose it but get 6 wks vacay a year while most start with 3 amd get 4 afte 8 years). Have to use it within 3 years after eligibility. It's a retention play, not just a reward. Part of the culture. We see attrition drop in years 3 and 4 then a little spike after 5, 10, etc.