This is what we give guarantee on:

• The factory test data is guaranteed to repeat when you receive new tubes.
• All specified parameters, and the good sound of the tube.
• Gas development, the getter flash, or anything else related to bad vacuum.
• All mechanical issues, like loose contacts, broken off parts, loose tube base, etc.

- You may be asked for factory test data, warranty information, and serial number, so be sure to bring it with you.

Standard Guarantee, without registration:

• 90 days
  
  This is only for the first user who purchased tubes on the official Stradi website.
  
  - Please remember your e-mail address when ordering the tubes.
  The service verification process will be done through your e-mail address.

Extended guarantee, with online registration:

• 1 year manufacturer guarantee in case of bad vacuum, mechanical issues.


- This is only for the users who bought tubes purchased from the official Stradi website. So please make sure to fill online with warranty card information, receipt information, serial number within ten (10) days from the time you received the vacuum tubes of your purchase.

Conditions:

• This extended, 1 year manufacturer guarantee program is limited to customers who purchased tubes via the official Stradi website.
• The guarantee begins with the date of receival, and is only valid for fully unused tubes.
• For extended guarantee service, online registration must be done within 10 days after receival.
• When a tube is replaced, the original guarantee start date is unchanged.
• A copy of the original invoice must be supplied upon request.
• A copy of the warranty card, tubes' serial numbers and e-mail address when you purchased from the Stradi site must be supplied upon request.
• When the failure reason can not be cleared without it, we may require a copy of the amplifier circuit diagram.

Additional costs:

• It is possible that we replace tubes for a period of 12 months if the sale was registered by the first owner, within 10 days after receival.
• A loose/broken tube base is repaired free of charge during the entire guarantee period.
• You will be responsible for paying for your own shipping costs for returning your item. Shipping costs are non-refundable.
  We strongly recommend using a trackable shipping service and purchasing shipping insurance (DHL/FedEx).
• Buyers are responsible for import duties, taxes and charges related to customs clearance.
• For the tubes returned to us because the buyer failed customs clearance or did not receive the item,
  if the buyer wishes to re-deliver the tubes,
  we charge 50% of the item price from the buyer as a handling charge.
  In this case, the seller ships via DHL/FedEx and the buyer is responsible for the shipping costs.
  Refunds are not possible even if the buyer does not wish to re-deliver.

Returns:

• Items returned to us without an return number assignment will be rejected. In that case, please remember that we do not send it back to the sender and we are not responsible for the shipping costs. Before returning the items, please contact by e-mail first and get a return number from us.
  To complete your return, we require a receipt or proof of purchases.
• Returning items are for repair or exchange only and customers are responsible for shipping costs.
• Purchased vacuum tubes can be exchanged only for the fault of the manufacturer.
• If the customer receives a tube that is different from the model ordered, we will bear the cost of reshipping. In that case, we will pick up the goods from DHL/FedEx. For smooth exchange, please do not return the item without consulting us. If you send an item and there is a problem, we are not responsible for anything.
• After delivery is completed, if the tube does not work or have any defects due to shock during delivery,
  please contact us via email or WhatsApp within 2 days after you receive the product, and we will take action for the customer to resolve these issues promptly.
  
  If the tube is clearly defective due to shipping shock or if the manufacturer's fault regarding the vacuum tube is fully proved, we will replace it with a new tube and bear the round-trip shipping cost.

Refunds:

• We do not offer refunds for electron tube purchases.

In our policy, we consider tubes as used ones once it has been sold and shipped to buyers.
Thus, we recommend the buyer to discuss the problem with us if there is any errors using with your vacuum tube.

This is excluded from the guarantee:

• Damaged or missing serial number on the tube.
• Tubes not normally burned-in.
• Tubes with an issue, which were continued to use after the occurrence.
• Tubes used with electronic circuits for filament heating or anode current control, which we have not approved.
• Tubes with serialized filaments, for instance two 5V heaters in series, heated with 10V.
• Failures not caused by Stradi (ZeroMountain company).
• Tubes which are electrically in parallel, without method for individual bias.
• Noise with tubes in some specific pre-amp, amp, driver etc.
• Tubes operated above the maximum ratings.
• Tubes that have been cryogenically treated.
• Tubes used in stand-by circuits, keeping the tube in stand-by mode for longer than 2 hours.
  Stand-by mode means filament glowing with no current.
• Tubes that are used in particular amplifiers, for which we do not recommend to use our tubes.
• Tubes showing a spark at switch on or off. This is an amplifier problem, which may be solved.
• A vacuum tube in which overcurrent flows due to a defect in the vacuum tube bias circuit voids the guarantee.
  For example, use of bad coupling capacitors and trim-pot malfunction, etc.