To save on the cost of paper and chemistry, it was common practice to do a series of test exposures before using full size sheets of paper and their associated chemistry. This little gadget let you expose the same portion of a negative at four different times for comparison.
In the summer of 1984, I was scheduled for kidney surgery. A few months earlier a neighbour ran over a cotton tail nest killing the mother rabbit. The little babies scattered like leaves in a wind storm. I rashly told my youngest that she could keep any kits she caught. Four cotton tails later, I scrambled to fit out an old dog crate with chicken wire to house the little things. The bunnies began drinking on their own just before my surgery. That fall, we released all four at Springwater Park in Midhurst, Ontario. A year later, I took this picture of my youngest girl on a visit to see the rabbits. I used my Leica M4 to take both the young bunnies and my daughter.
Months later, to decorate my office, I printed a few 16 x 20 photographs including one in this series on Ilfobrom paper. The prints were mounted by me in metal frames without separate masking. I printed the whole negative including a narrow random band of light created by my Durst enlarger as it slightly overshot the negative.