369DRONE Arm 4mm for MIROKU PRO Frame Review

The Arm 4mm for MIROKU PRO Frame is a carbon fiber arm listed at $6 as a single option. The listing calls it a custom fit for the MIROKU PRO Frame and gives the thickness as 4mm. The listing describes the arm as aimed at speed and responsiveness and says this comes at the cost of reduced crash tolerance.

Specifications

Options and pricing

Only one variant exists here, priced at $6, so nothing changes with size or color. The size row says 4mm, the material row says carbon fiber and the Fits row names the MIROKU PRO Frame. The listing does not say whether the price covers one arm or a set, and it gives no length or weight.

How it compares

Two other $6 arms sit beside this one: the Arm 5mm for MIROKU Frame is 5mm and listed for the MIROKU Frame, and the PRO Trinity Arm 4mm for MIROKU PRO Trinity Frame is also 4mm but has a Fits row of PRO Trinity. The three differ by thickness or named frame, not by price, so an arm for another frame does not replace this one.

Shipping and processing

• Processing. The store's shipping policy says every order, including orders placed through the Shop app, ships from its warehouse in Japan and is dispatched within 1-3 business days after payment is confirmed (checked 2026-11-11).
• Shipping cost. The policy gives a flat 800 JPY inside Japan and 5,000 JPY to eligible countries for parcels up to 2 kg, and gives no rate for heavier parcels. It does not list the eligible countries; the store's country selector offers the United States, Canada, the United Kingdom, Australia and New Zealand, and the terms of service reserve the right to limit sales to any region, so the checkout is the final test. At the rate the store used for US prices when we looked (about 0.00642 USD per JPY), 5,000 JPY is about $32; the checkout shows the exact amount.
• Price against shipping. This listing costs $6, less than the flat international shipping fee above. The policy prices shipping per parcel up to 2 kg, so what an order of several small parts pays depends on how the store packs it, and the pages do not say.
• Duties and taxes. The policy says import duties, taxes and customs clearance fees are not included in the price or the shipping cost, are charged to the recipient by the carrier (it names DHL, FedEx and Japan Post) and are outside the store's control. It declares the full value of the goods on customs papers and cannot mark a parcel as a gift or declare less. A parcel held for unpaid duties is not delivered, and if the carrier sends it back the return shipping is deducted from any refund.
• Tracking. A tracking number is issued once the parcel ships. For international parcels it can take a few days to show up, and it can change when the parcel is handed from one carrier to another.

Returns and warranty

• Returns. The store's refund policy gives 30 days after receiving an item to request a return. The item must be in the condition received, unworn or unused, with tags and in its original packaging, and you need the receipt or proof of purchase. Use the contact page first: if the return is accepted the store sends a return shipping label and instructions, and items sent back without a request are not accepted. The policy does not say who pays the return shipping on a change-of-mind return. Refunds go to the original payment method within 10 business days after the store has received and inspected the item (checked 2026-11-11).
• Not returnable. The refund policy lists custom products (special orders and personalized items), perishable goods, personal care goods, hazardous materials, flammable liquids and gases, sale items and gift cards. The legal notice, which is in Japanese, adds made-to-order items, digital downloads once downloaded, and goods whose value was lost through the buyer's use or modification. For an exchange the policy says to return the item and, once the return is accepted, buy the new one separately.
• Damaged or wrong items. The refund policy asks buyers to inspect an order on arrival and to contact the store at once about a defective, damaged or wrong item so that it can evaluate the issue and make it right. The legal notice says the store exchanges or refunds such an item at its own cost.
• Warranty. The shipping policy, refund policy and legal notice describe no warranty, and we found no warranty page. The terms of service say products are provided 'as is' except as the store expressly states, disclaim warranties, and are governed by Japanese law. Many of the parts this store sells are made by other brands; nothing says whether the store or the maker handles a fault that appears after the item has been in use (checked 2026-11-11).

Before you buy

369DRONE describes itself as an FPV racing drone brand from Japan. Its About page says the founder, Daichi Sakakibara, spent over a decade as a test driver at Toyota Motor Corporation and builds products with experience from racing. These are the store's own statements (checked 2026-11-11).

The store is in Japan and quotes yen. The price on this page is its United States dollar price as of 2026-11-11; the store converts at its own rate, which moves, and a visitor in another country can see a different amount or currency.

The legal notice, written in Japanese, says the products are meant for FPV drone racing and hobby use, asks buyers to follow the Aviation Act, the Radio Act and other laws, and says the store takes no responsibility for damage caused by use that breaks the law. Those are Japan's laws. We have not checked what applies where you live and we do not say whether this product can be flown or operated legally in your country.

The English refund policy takes back items that are "unworn or unused", while the Japanese legal notice says, as we read it, unused and unopened, so check the condition rule with the store before opening the package. We have not read any independent review of this product or of the store.