Based on our experience in AR building , it appears we're always in search of small parts that seem unimportant, until they are, because we can't find any. Our AR15 detents and small parts kit composition reflects our experience, it includes the following (1 of each unless otherwise specified):
Take down / pivot pin detents (x4). We've lost our share of these tiny spring loaded misiles, so we include extras ( it's cheaper than fitting a GPS on them). Coating of these detents may vary.
Bolt catch plunger
Bolt catch roll pin (not pictured)
Buffer retainer pin
Trigger guard roll pin
Safety detent (x2). Safety detents should be considered wear items, so we include an extra.
Reasonably priced with shipping included, we think it will make many AR owners happy :)