6550 (6550A-98) 6550B is similar to the KT88 series tube and can be used interchangeably.
For delivery time:
Generally, we will dispatch the items within 7 days upon order confirmation; some items may need 15~21 days to get ready for delivery, then we will try our best to dispatch as soon as possible, or we will contact you and offer advice.
For Bulk order:
If you would like to place a bulk order, please contact us for better price and better delivery cost.