With the kSRO update from today, Joymax gave us some facts about new silk items that may come in the future:
Connection ticket
Quite simple: When you use the ticket, you can login to the server all time even when it is crowded. The item has no other function but this, so it is only useful if you don't want to buy a full premium ticket. ~A reason to disable the anti-goldbot-statues on iSRO again

Bronze EXP/SP tickets
A bronze EXP ticket can either run for some hours only or some days (from 5 hours up to 14 days different tickets will be available). It will give an EXP bonus of 20% while killing mobs, no SP-EXP bonus. For getting 20% SP-EXP, a bronze SP ticket will be available too.
50%/100% EXP/SP tickets
These tickets will run 1 hour and, just like bronze tickets, increase EXP or SP depending on the ticket you buy. These tickets can increase EXP or SP gained either by 50% or 100%.
HP/MP recovery ticket
HP/MP Recovery tickets will decrease the potion delay of characters. In the description it says that chineses will have a 1 second potion delay while using the ticket, and european characters will have a 15 second delay (what actually doesn't change it lol). These tickets last either 1, 2 or 3 hours.
Silver Premium / Premium / Premium Plus
The "old" premium tickets will be added for shorter times, like 1 or 2 weeks.
Again, a new silk item in kSRO: The dungeon tickets! Normally, you have a limited number of times you can enter a dungeon (like 2 times per day in Pharaoh Tomb [5 with Premium+ in iSRO] or 1 time per day for the Forgotten World). Now, with this silk item you can enter a dungeon directly as often as you want.