The Breitling Watch Source Forums

Right, the boxed sliderules are identical to the non box ones, they just have an additional print colour added afterwards - the red / orange. The underlying sliderule should always be the same it's just more or less visible depending on the little variances in the overlay print.

Great pic. Now I understand. I have two boxed 10 and there's no black stroke visible, so I thought it must be reprinted.

here is another example, red "boxed 10", the red stroke is directly above the black, so not as visible: