Hello! Anyone knows where can I buy Darton sleeves 800-420? If you can help me please share the link to buy this item. Thanks

Where are you located? I found many listings on a google search of your part number. Here’s one: https://www.ebay.com/p/Darton-800-42...-5l/1941104955

I think Chris White is a great resource as well.
http://www.944enhancement.com/html/services.html

On Darton’s website there is a list of distributors. Contact one closest to you and they will order a set for you. Which shop is fitting them for you? If they’ve worked with Darton sleeves before then they likely work with a distributor, if they haven’t fitted Darton sleeves choose another shop.

https://www.vividracing.com/-p-15077...saAgngEALw_wcB

According to their site they are in stock currently.