This item is a resin detail parts set for use with military vehicle kits.
Accurate Armour is known throughout the modeling world as a top-notch maker of highly detailed multi-media conversion sets, accessories, and full kits, with a mind-boggling selection of subjects.
From the Accurate Armour website:
A comprehensive 1/35th scale resin and etched brass interior set by Jon Bottomley. Designed to fit the AFV Club M3A3 plastic injection kit.