my range for attacking limps first hand readless would be a8+, k9+, QT+, JT, with maybe an extra kicker down if the hands are suited, this is for 25bb.I think 3.5x is best for this effective stack size, though I also think its ok to raise a little less with the weaker end of this range. The reason is a hand like QJ is a lot more likely to dominate a limp call range than a hand like AK (so less need to punish with sizing), and on top of this there are more profitable bluff/value boards when you rase a hand like QJ compared to a hand like AK, (for one instance you basically always win A high flops in these spots, so an A high flop with QJ is gong to be much better than a Q high flop with AK in terms of bluff value, and a top pair Queens is going to get a more value on avg than a top pair ace)When we get shallower we can gii with a wider range to a limp readless, so shallower we would just shove weak Ax, Kx, and small pairs over limps (any Ax below 20bb, any Kx below 12bb, small pairs at any depth). We make non all in raises with hands that we want to get our opponent in with a wider range, so a hand like QJ would be best for a 3x when facing a limp 13bb, where as A2 would be much better to just shove.Of course be aware of reads too, your reads to into your opponents limp range (which shouldn't come from just what they limp, but also deductively from what they are raising) will be necessary to tinker with this readless strategy and make it optimal vs the player in question.