In the name_get method available at PRODUCT module
For more info on NAME_GET method : https://doc.odoo.com/6.0/developer/2_5_Objects_Fields_Methods/methods/#osv.osv.osv.name_get

    def name_get(self, cr, uid, ids, context=None):
        if isinstance(ids, (list, tuple)) and not len(ids):
            return []
        if isinstance(ids, (long, int)):
            ids = [ids]
        reads = self.read(cr, uid, ids, ['name','parent_id'], context=context)
        res = []
        for record in reads:
            name = record['name']
            if record['parent_id']:
                name = record['parent_id'][1]+' / '+name             to         name = record['parent_id'][1]+' > '+name
            res.append((record['id'], name))
        return res