Hello. I have a rock river arms upper with m-4 profile. It is a flat top and wil come with an LMT rear sight. It is an awesome uper! It is super accurate. I've only put about 500 rounds through it at the most. It has m4 hand guards and a side sling mount under the front sight tower. Complete with bolt and chg handle. I would like to get 400 for it. please let me know! thanks!