How a skin enters the inventory
Spend 50 Credits to open a standard case. The roll can be a weapon finish, and a much smaller share of rolls are gloves or knives. Published estimates put special items around 0.5% to 2%. That is a range from community writeups, not an official rate card, so do not treat it as the odds printed in your case.
StatTrak odds were reported as raised from 1.42% to 5% during the Headwind trading updates. Confirm the current case text before you count on that figure.
Event cases, codes, and shop bundles are the other paths. A code that once paid a case is in the expired archive and should not be expected to drop a knife now.
The 100 value door
Trading servers stay locked until tradable items in the inventory add up to at least 100 value. Opening cases is the usual way to reach that number without a trade. Value lists used by players move, and two traders can disagree. Compare items inside the trading server you are actually using.
What not to mix up
Round cash resets with the half and buys guns. Credits buy cases. Inventory value is a third number and only matters for the trading door and for how players price a trade. A free knife code from 2018 does not raise today's Credit balance.
Headwind has said current skins, inventories, and pins are planned to carry into Counter Blox 2. That transfer is not live on this place.
Trades outside the game
Use the in-game trading servers once you have 100 value. Off-platform sales and item-for-item deals outside Roblox are a common scam path. This guide does not list a specific penalty because enforcement is Roblox's, and it does change. If a deal asks you to leave the trading window first, stop.