Database
[{"_id":ObjectId("5f281caf3494701c38711e96"),"WidgetId":"0233261","Specs":[{"WidgetType":"A","AmountLow":NumberLong(0),"AmountHigh":NumberLong(0)},{"WidgetType":"A","AmountLow":NumberLong(0),"AmountHigh":NumberLong(500)},{"WidgetType":"A","AmountLow":NumberLong(1),"AmountHigh":NumberLong(1000)}]}]
Query
db.collection.aggregate([{$addFields:{Specs:{$filter:{input:"$Specs",cond:{$and:[{$eq:["$$this.AmountLow",0]},{$gt:["$$this.AmountHigh",0]}]}}}}}])