These are stock items manufactured with Hitachi branding, marked as made in February 2016.  They have been tested in a tuned input tuned output small signal amplifier at 18MHz and exhibit a gain of at least 18dB. 50 randomly tested from a packet of 100 pieces tested good.  The price is for a pack of four pieces.

Tracked carriage is quite high.  If you use a computer instead of a mobile phone to order then you can click to buy several items up to a value of 50GBP and ask for an invoice.  I then adjust the postage and return to invoice for acceptance and payment.