There are many manufacturers who produce and sell padlock shims. The problem is that most of these sets of shims come in a bafflingly large array of sizes... sizes which range from "comically small" to "ridiculously large" (Such extreme sizes of shims are seldom useful in typical padlocks)
This set of shims are exclusively in the "medium" size (also known as "the normal and useful" size) of padlock shim. These come in a 5-pack since, while padlock shims are a consumable tool that must be replaced after a number of uses, not everyone needs a 20-pack. So save yourself some money (and save yourself the frustration of getting oddball sizes of shim) with this 5-pack for a bargain price.