Product - see also detailed description
2nd class blue Machin security from retail booklet, 2017, coded ROYAL MTIL M17L
The M16L version of these booklets, with security backing paper type 2, appeared in mid-June 2017.
Cylinder numbers are W6 (blue) W1 (iridescent) W3 (phosphor).
SG U2963 - also used for other years
Price is for a single stamp.