Sports betting can at times be purely down to the numbers, but it's unfathomable to consider what's so special about 138 that a cutting-edge sports book has adopted it as their name. This Asian-based company are certainly followers of UK-based sports, as they've been the principle sponsors of EPL club Watford for five seasons now. Whether you follow the Hornets or not, you can claim a £10 bonus token when you sign up at the 138 site.
A £10 bonus token is the maximum you can claim with this offer, and a £5 bonus token is the minimum. Once you have signed up with the site, just make a qualifying deposit in line with the size of bonus token you want. Note that only deposits using credit or debit cards will be honoured with a free bet token, not eWallet transactions.
You must make a qualifying bet (singles and combos only - not system bets) to the value of your deposit up to that maximum of £10. Once that bet has been settled, you will need to contact support at the site to claim your free bet token. Once you have done this, your free bet token should appear in your account.
As is typical with these kinds of offers, your free bet token cash cannot be withdrawn, however, you are completely free to withdraw any winnings that you make with your free bet, and as real money without any further wagering expectations.
You can read more about the superb 138 sports betting site, including information about bonuses and promotions.