How to read holes matrix?
6M6d50 or 6xM6/d50 means 6 bolts with diameter M6 spaced at 50 mm in diameter.

Bolt tightening torques:
M6 – 8 Nm / M8 – 12 Nm

When to use distance plate?
After installing the propeller the minimum space between propeller and small pulley should be approx. 3-5 mm.
If the distance is less, use the distance plate. Engines depending on the version and year of manufacture may have different designs, so the mutual position of pulleys may vary. The need for a spacer will usually occur when the plane of the small pulley is not withdrawn with respect to the plane of the propeller mount, but is on a level or withdrawn slightly. Be sure to check this before the first run! The situation may also depend on the specific model or propeller diameter, so check this on a case-by-case basis.

If the engine uses a head cooling fairing (their shape depends on the version and manufacturer), the minimum distance of the propeller at rest from the fairing must not be less than 10 mm.
If the distance is less, a spacer should be used.

Suitable spacers can be ordered together with the propeller (section Accessories). In special cases and in case of urgency, sometimes a pressure flange (it happens to be in stock) or a self-made spacer made of an equal thickness of plastic (if thin, there may be several layers) is enough.
Such less professional distances do not have a centering flange. This is not a problem, however, because the fleXer propellers position perfectly on the set of mounting screws and the flange is completely unnecessary.

Propeller tip
Before starting the engine with a fleXer propeller for the first time, it is necessary to carry out a check of the minimum distance between the propeller tips and the elements of the basket (e.g. strobe, tubes, net). Minimalna odległość od końcówki śmigła w spoczynku do elementów kolizyjnych wynosi 11 cm w osi kierunku lotu. Depending on the propeller model, the minimum distance may be less (consultation required).