Small black (or gray sometimes) instrument panel bulb socket for the 60's & 87 Camaro & Firebird - and most GM Vehicles in between.
Has a 1/2 inch hole (12.25 mm roughly)
(there is also a larger 5/8 socket also. Listed # PW17967
Need bulbs...???
Stardard bulbs that fit this socket search for XL194.
If you want also .. you can replace the bulbs that go into it LED bulbs.. if you want.including some coloured ones..Pair set PWLED194PR