Market-style CSAs let members choose what goes in their box from the farm's harvest offering at each pickup. Members typically get a "credit" based on share size and fill their bag from bins of produce, sometimes with tiered pricing (e.g. "take 8 items plus 2 premium items").
Strengths: higher member satisfaction (people get what they'll actually eat), reduced food waste, a more market-like experience. Weaknesses: more labor for the farm, requires dedicated pickup space and staff, can frustrate members who show up late when the best items are already picked.