I specialise in these ecu kits for MX5 cars 1989 - 2005.
This set is from a 1998 - 2000 MK2 1.8 car fitted with 6 speed gearbox.
This is the same part as European BP5Y - 279700-860
In addition to the parts shown you will have access  to my knowledge of these parts are what is required to repair your vehicle and assurance that these parts will cure any ecu/immobiliser fault with a car fitted with this specific BP5Z ecu.
If you have an issue with an MX5 fitted with another ECU please contact me through ebay.
I have nearly 70 sets with factory immobiliser in stock for the MK1 - MK2.5 cars.
B6HB, BPU2, B6ML, BP5C, BP5Z, B6MV, B6NB, BP6M and BP7P.