There are currently on a backlog. The estimated date for shipping is early July with limited qty available.

These are the keepers needed to run an aftermarket valve spring setup on your Miata. This is the same design as the later NB keeper so it's often sourced when building older cylinder heads. 

Included:

32x Keepers/Valve Locks - All 1.8, 1.8VVT, 1.6 compatible.