Nothing is more important when bikepacking than keeping your essentials dry. That could be your sleeping bag, insulated jacket, or even small bits and pieces like wallets, phones and paperwork. A dry sack is therefore a must, not only keeping kit dry but also organised; we have a bag for sleeping kit, a bag for warm kit etc - you get the idea - and they can all be unpacked onto wet ground without fear of contaminating the contents with water. The Blockerlite is thin and light, yet waterproof with a roll-top, and has a square profile for easy stacking and packing.
The Blockerlite is perfect for bikepacking due to its extreme lightweight (just 44g for our 10 litre) and thin and pliable fabrics, easily stuffed into hydration packs or frame bags, yet hardly taking up any more room than its bare contents. Although it is only a minor feature we did like the more rectangular shape Seal Line have built them into, fitting our bags a little better than the tradition round sack shape.
The seams are all welded rather than sewn and taped which apparently makes them 50% stronger, and we can't argue with that as ours has survived very well. Just use common sense and don't pack anything sharp that could puncture the material as, although surprisingly tough, it really is featherlight and vulnerable to piercing.
A great, wafer thin yet tough range of bags, ideal for bikepacking where they slide into the smallest corner of your luggage.