Selling straddles and strangles are indeed capital-efficient strategies, but they also come with a higher level of risk. Here's why:

1. _Capital efficiency_: Selling straddles and strangles requires a relatively small amount of capital, as you're only required to post margin for the potential losses.

2. _High probability of profit_: These strategies involve selling options with a high probability of expiring worthless, making them attractive for traders who want to generate consistent income.

3. _Limited upside_: The profit potential is limited to the premium received from selling the options.

4. _Unlimited risk_: However, the risk is unlimited, as the seller is exposed to potentially large losses if the underlying asset moves significantly.

A _short straddle_ involves selling a call and a put option with the same strike price and expiration date. A _short strangle_ involves selling a call and a put option with different strike prices, but the same expiration date.

To manage risk, it's essential to:

1. _Understand market dynamics_: Be aware of market conditions, volatility, and potential events that could impact the underlying asset.

2. _Set stop-losses_: Implement stop-loss orders to limit potential losses.

3. _Monitor and adjust_: Regularly monitor the position and adjust as needed to manage risk.

Remember, selling straddles and strangles is a advanced options strategy, and it's crucial to thoroughly understand the risks and rewards before implementing it.