Bertie Mk 4
From threeA Wiki
Bertie Mk 4 is the rumored next release of the Bertie type robot. Very little is known about it - it has similar proportions to a Bertie Mk 2 , and it's an "Infantry Bertie" . These mentions came in a discussion about WWR scale Bertie Mk 2 Colorways, so it can be inferred that a Bertie Mk 4 would show up first in WWR scale.