Slug Buggers is a waste product from the wool-processing industry. The material, which is dirty or knotted wool, would otherwise be burned so it’s a very eco-friendly product. Applied around the surface of pots or individual plants in the ground, the pellets form a rough carpet of fibres which slugs and snails won’t cross because they find it uncomfortable, and it also dries them out. So along with protecting vulnerable plants, these pellets form a moisture-retentive , weed-suppressing mulch. Long term the pellets will provide small amounts of nutrients, too.  The handy size of tub with a handle is easy to carry around the garden.  The only downside is the cost but you could club together with neighbours or fellow allotment holders and buy three tubs because this way, you would forego the postage charge.’ Star Score: ***** Features, *** Value – Total Score 8/10’.
Grow, Cook and Eat, Issue 1, 2009

...really good, new barrier in the form of pellets made of recycled sheep's wool. When spread around my Rudbeckia occidentalis 'Green Wizard', which was shredded to bits last summer despite my best efforts, it has formed a dense matted layer that the beasts have not yet breached. It seems to be better than granular barriers, which I find scatter about too easily. I am told that, as a bonus, the wool rots down and feeds the soil. I like the name, too: Slug Buggers.
Helen Yemm for Thorny Problems - Ask the Expert, Telegraph Gardening, 5 April 2008

Generations ago folk used sheep's wool to protect their crops and its only now that a proprietary product has reached the gardening market. Slug Buggers is a waste product from the wool-processing industry. The material, which is dirty or knotted, would otherwise be burned so it's very eco-friendly.
I could see the wool fibres springing out of the pellets on opening the lid. There was also a strong animal odour.
Applied around the surface of pots or individual plants in the ground, the pellets form a rough carpet of fibres which slugs and snails won't cross.
So along with protecting vulnerable plants, they form a moisture-retentive, weed-suppressing mulch and long term, the pellets will provide small amounts of nutrients.
The handy size of tub with a handle was easy to carry around the garden.
Star Score: 8/10 with 5* for features and 3* for value
Shop Around by Julia Heaton, Amateur Gardening magazine, 12 April 2008

Kitchen Garden magazine reviewed this product in December 2007:

...The woollen slug pellets offer a natural yet effective way of deterring the number one pest.

The pellets are made from reclaimed material from the wool processing industry and no other materials or chemicals are added, making the pellets 100 per cent natural.

Once wet the pellets form a rough carpet with small needle-like fibres that slugs won't cross. The slugs are physically deterred rather than being killed.

... is also a rich source of nitrogen and an effective mulch and weed suppressant. Being a natural product, it is safe for plants, children, animals and the environment.