The OPS-Store Factory shows how one can install the hop-up on block they made a Tokyo Marui MP7... "OPS-Factory, the workshop division of OPS-Store, has developed a custom-reinforced Hop Up block for AEP MP7 Tokyo Marui - Well - Umarex airsoft replicas. This part, made from CNC 7075 aluminium, will correct the defects of the original blocks, which break very frequently.