K31 diopter? Never heard of it.
Front sight mounts just behind the original front sight and is held on by four screws(4-40?).
Rear sight is held by by one large screw clamps a block from inside the receiver in the thumb cut.
I suggust centering the left /right adjustment and lowering the height all the way down before mounting it.
First shots should be used to line up the front sight housing to the centered diopter to enable you to have the most left right windage available to you.
This means loosening the four front screws and moving the front sight housing in the opposite direction you want the impact to go.
(Note: if your rifle shoots fine with irons, use the irons to help you line up and do the above to get within a few inches of your aim mark at 100yds.)
You will not have much, if any, elevation adjustments available to go below 100 yds with most rifles, but will have enough to go to 1000 yds with the latest P/S Diopter. Some rifles needed a thin shim between the top of the barrel and the front sight assembly to get a 100yd zero. Steel shim 0.015” thick under front sight clamp lowers POI almost 2 MOA, if necessary, for 100 yard shooting. A Post front sight will give a lower impact than a ring type.
Elevation range adjustment was tested at 37.95 true MOA on the prototype
Front sight takes M18 size apertures. Kit comes with one to get you going. Could be from 2.8mm to 3.2mm
I use a Gehmann 522 adjuatable aperture that has a range of 2.5mm to 4.3mm. Size you need depends on black of target size, distance, and light conditions that same day, and how much sleep you got the night before.
Rear sight on the Swiss Products P/S diopter uses standard Anschütz iris thread which most of the latest irises use.
One basic Gehmann or Anschütz rear iris comes with kit.
Original W&F Swiss diopters use a smaller propriorty thread size and pitch.
Adjustments on the Swiss Products are basically 1/4 MOA in direction you want inpact to go.
Adjustments on W&F diopters are the same, but as in all German sights which have the word "bye" on them, adjust "BY" where the shot was, not where you want the shot to go.
Direction H(oche) if your shot was high, T(iefe) if your shot was low, L(inks) if your shot was on/by the left, R(echt) if shot was on/by the right.
Need anything else?