If you decide to buy a set of four bolts ("secret") and an adapter key, we advise you not to rush. Having walked through just one car market, we counted 12 varieties of such sets. Prices for them fluctuate depending on the material from which they are made and the originality of the design.
There is an obvious consumer product, which is an eccentric bolt with the same key. A bolt with a large eccentric head has no protection against twisting with a gas key. This option may be of interest to owners of those cars that have alloy wheels with a deep seat for a "secret". The price of such protection is from 3 to 5 USD.
Bolts with a rotating protective ring and the same eccentric cost up to $10. But the ring makes unpleasant sounds when driving, creating the impression that a rope with tin cans was tied to the car. Many get rid of this noise by twisting a simple rubber band from curlers under the base of the bolt.
Having reached the price of 15 USD, the secret bolts begin to resemble not "ugly ducklings" who are tired of rusting on the counter in the open air, but white swans, proudly raising their steel heads above a pile of all sorts of washers, nuts, screws, gaskets lying nearby. As a rule, these "secrets" are distinguished by high quality of execution, appropriate heat treatment and the presence of a protective coating.
There are also many design options. All of them, as a rule, have a protective ring fixed to the bolt through a rubber seal, eliminating extraneous noise. They have not one, but two keys (one spare). The forms of the "secrets" themselves are quite varied. Starting from the simplest, but already refined eccentrics, to intricate splined connections: these, as it seems to us, are the most reliable and convenient for installation.
The last class includes those costing from 15 to 25 USD. These examples seem to have come straight from the canvases of avant-garde artists. Here you have "trefoils", and nuts of irregular shape, and a truncated cone, and bolts with holes for a key, reminiscent of the sign "Deaf at the wheel". All of them are made with a protective ring. There are very convenient and practical ones, but there are also those that raise doubts about their suitability for work.
When buying "secret" nuts in our city, you are usually not insured against the fact that the intruder does not have the same key. The fact is that manufacturers are unlikely to change the sizes of bolts and keys to them, ensuring the individuality of each set. Therefore, if you install "secret" nuts, then buy them in another city. Or order them specially from a familiar turner. In this case, the likelihood that your wheel will end up with a neighbor in the parking lot is already less, but...
And yet, there is a point in installing secret bolts - technically inexperienced guys are excluded from the number of potential claimants to your wheels, additional time is required for "unauthorized" removal of wheels, and as a result of careless manipulations by competent intruders, the alarm installed on the car may have time to work. Unless, of course, the intruders are competent enough to "disarm" it.
We will not go into technical details, thus tempting the "unconscious". Let us just say that if the owners of light-alloy wheels with recesses hiding the bolt heads can "sleep peacefully" with one "secret" bolt per wheel, then it makes sense to fasten steel wheels with three or four "tricky" bolts (or nuts), preferably different ones, which is quite expensive and troublesome. However, healthy sleep is more expensive.