Buy RS3 Sirenic scale
The RS3 Sirenic scale is a members-only crafting material in RuneScape 3. Scales are used to make sirenic armour, one of the best ranged armour sets in the game. They are tradeable and stackable, so they are easy to hold in large amounts.
Getting scales by yourself is slow. Most monsters that drop them need a Slayer level of 78 or higher, and drops are still rare even then. A ring of Wealth or a Slayer task does not make scales drop more often. Buying scales skips that grind.
Making sirenic armour takes level 91 to 93 Crafting. A sirenic mask needs 14 scales, sirenic chaps need 28, and a sirenic hauberk needs 42. A full set takes 84 scales and 6 algarum thread. Scales are also used to make Elite sirenic repair patches, craft the Enchantment of dispelling, and recharge dyed sirenic armour.
Sirenic scales stand out as the only tier 90 armour material that does not come only from bosses. If you want strong ranged gear or want to train Crafting with high-level materials, sirenic scales are the item to stock up on.