BTCUSD/ETHUSD/LTCUSD is a perpetual contract priced on the Bitcoin/Ethereum/Litecoin composite index called Fair Price (price is built from multiple external sources).
This contract is settled in BTC, quoted in USD. Each contract has fixed value of 0,1 mBTC per $1 price. It means that with every price change of $0.01 the contract value changes by 100 satoshis. The relation between contract price and contract value is linear and does not change with contract price.
There is no expiration date for this contract. Instead, funding payments are exchanged between contact parties. BTCUSD/ETHUSD/LTCUSD uses a premium index to calculate funding rates. The underlying interest rates are quoted in BTC.bon/ETH.bon/LTC.bon and USD.bon symbols, and the premium rate is quoted in the BTCUSD.premium/ ETHUSD.premium/ LTCUSD.premium. These are used to calculate the final Funding Rate. Funding is paid and received every 8 hours. PrimeBit does not charge fees on funding payments.