iYoYo has developed two variants with a well-known German manufacturer of silicone oil that specifically meet the needs of YoYo players :
Thin - used to care for wide ball bearings (e.g. size C), which should have as little response as possible (i.e. only come back with the bind at hand) and require a long sleeper. The oil is so thin that it looks almost like water. Perfect for YoYo ball bearings! Recommendation: Apply a drop if the bearing becomes unintentionally "responsive", is loud or has been cleaned in lighter fluid. If everything goes well: don't do anything, play!
Thick - Used for ball bearings from Loop yoyos (e.g. Loop900, Loop1080) because they require a high response. The thick oil is also ideal for making entry-level yoyos with narrow bearings (e.g. ONE, narrow bearing from the iYoYo 2) responsive again (so that the YoYo can easily come back to you by twitching). Recommendation: put a drop in stock for Loopyoyos before each line change, for entry-level yoyos only if necessary if the YoYo no longer comes back by hand by twitching.
The bottles contain 25 ml each. This extends the experience easy for 2 years under normal play behavior.