SFX Mini Single Speed Freewheels
3/32" or 1/8". 
M30 x1 thread.

Suitable for BMX

13, 14 or 15 Teeth sizes.
2 pawl mechanism
Ball bearing
Fits to Mini type M30 x 1 threaded hubs only.
(M30 is typically found on BMX Flip-Flop hubs)
Note: Always apply a little grease to the threads when fitting.
Use TLSF2 Freewheel remover to extract. 2STTLSF2

ISO 1.375" x 24 TPI threaded SFS series freewheels 16-22T are also available.