There’s 2 different 1-5 Middy elastics & they’re both green coloured, easily mixed up.
Micro-Shock Elastic 0.8mm diameter, fish size 2oz to 2lb. For Silverfish.
Micro Shock Core Elastic 1.25mm diameter, fish size 2oz to 3lb. For Silverfish & F1s. This has only been out a couple of months, unlike the above it’s a hollow (the older one has different core & outer layer materials but isn’t a hollow). I’ve been using this one in the autumn for decent roach, averaging 6oz with bonus fish 1lb-ish & just started using it for F1s & skimmers.
There’s also a conventional solid, which is also bright green & is rated 3-4.